Estimation of respirable dust exposure among coal miners in South Africa.

Science.gov (United States)

Naidoo, Rajen; Seixas, Noah; Robins, Thomas

2006-06-01

The use of retrospective occupational hygiene data for epidemiologic studies is useful in determining exposure-outcome relationships, but the potential for exposure misclassification is high. Although dust sampling in the South African coal industry has been a legal requirement for several decades, these historical data are not readily adequate for estimating past exposures. This study describes the respirable coal mine dust levels in three South African coal mines over time. Each of the participating mining operations had well-documented dust sampling information that was used to describe historical trends in dust exposure. Investigator-collected personal dust samples were taken using standardized techniques from the face, backbye (underground jobs not at the coal face), and surface from 50 miners at each mine, repeated over three sampling cycles. Job histories and exposure information was obtained from a sample of 684 current miners and 188 ex-miners. Linear models were developed to estimate the exposure levels associated with work in each mine, exposure zone, and over time using a combination of operator-collected historical data and investigator-collected samples. The estimated levels were then combined with work history information to calculate cumulative exposure metrics for the miner cohort. The mean historical and investigator-collected respirable dust levels were within international norms and South African standards. Silica content of the dust samples was also below the 5% regulatory action level. Mean respirable dust concentrations at the face, based on investigator-collected samples, were 0.9 mg/m(3), 1.3 mg/m(3), and 1.9 mg/m(3) at Mines 1, 2, and 3, respectively. The operator-collected samples showed considerable variability across exposure zones, mines, and time, with the annual means at the face ranging from 0.4 mg/m(3) to 2.9 mg/m(3). Statistically significant findings were found between operator- and investigator-collected dust samples. Model

Quantification of Inherent Respirable Dust Generation Potential (IRDGP) of South African Coals

CSIR Research Space (South Africa)

Phillips, H

2003-08-01

Full Text Available Advisory Committee Project Summary Project Title: Inherent Respirable Dust Generation Potential (IRDGP) of South African Coals-SIM020604 Author(s): H.R.Phillips and B. K. Belle Agency: University of Witwatersrand Report Date: July2003... Related Projects: Health 607, Sim 02-06-03 Category: Occupational Health Applied Research Occupational Hygiene Summary Project SIM020604 was formulated to determine the Inherent Respirable Dust Generation Potential (IRDGP) of various South...

30 CFR 71.301 - Respirable dust control plan; approval by District Manager and posting.

Science.gov (United States)

2010-07-01

... District Manager and posting. 71.301 Section 71.301 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... plan; approval by District Manager and posting. (a) The District Manager will approve respirable dust control plans on a mine-by-mine basis. When approving respirable dust control plans, the District Manager...

Measurement of Lung Cancer Tumor Markers in a Glass Wool Company Workers Exposed to Respirable Synthetic Vitreous Fiber and Dust

Directory of Open Access Journals (Sweden)

Shabnam Abtahi

2018-01-01

Full Text Available Background: Occupational exposures to respirable synthetic vitreous fiber (SVF and dust are associated with many lung diseases including lung cancer. Low-dose computed tomography is used for screening patients who are highly suspicious of having lung carcinoma. However, it seems not to be cost-effective. Serum biomarkers could be a useful tool for the surveillance of occupational exposure, by providing the possibility of diagnosing lung cancer in its early stages. Objective: To determine if serum carcinoembryonic antigen (CEA and cytokeratin fragment (CYFRA 21-1 levels in workers exposed more than normal population to respirable SVF and dust may be used as indicators of progression towards lung cancer. Methods: An analytic cross-sectional study, including 145 personnel of a glass wool company, along with 25 age-matched healthy individuals, was conducted to investigate the relationship between occupational exposure to respirable SVFs and dust and serum levels of two lung/pleura serum tumor markers, CEA and CYFRA 21-1, measured by ELISA. Results: Individuals exposed to higher than the recommended levels of respirable SVF had higher serum concentrations of CEA and CYFRA 21-1, compared to controls (p=0.008 and 0.040, respectively, as well as in comparison to those exposed to lower than recommended OSHA levels (p=0.046 and 0.033, respectively. Workers with >9 years work experience, had significantly (p=0.045 higher levels of serum CYFRA 21-1 than those with ≤9 years of experience. Conclusion: It seems that working for >9 years in sites with detectable levels of respirable SVF and dust would increase the levels of known lung cancer serum tumor markers. Transferring these workers to sites with respirable SVF concentrations lower than the limit of detection in the air is recommended.

Characterization of respirable mine dust and diesel particulate matter

CSIR Research Space (South Africa)

Mahlangu, Vusi J

2015-11-01

Full Text Available This paper presents the preliminary outcomes to develop and optimize methods to characterize DPM and respirable dust samples for the following: Crystalline compounds Common mineral analyses Particle size distribution Elemental Carbon (EC...

Respirable dust meter locates super polluters in traffic

NARCIS (Netherlands)

Schmidt-Ott's, A.; Kurniawan, A.; Schrauwers, A.

2006-01-01

The Netherlands is having trouble with the EU standards for respirable dust (PM 10). The Dutch Council of State recently blocked a number of residential development projects because local conditions failed to meet the PM 10 standard. Research by the Nano Structured Materials group at TU Delft shows

Effectiveness of dust control methods for crystalline silica and respirable suspended particulate matter exposure during manual concrete surface grinding.

Science.gov (United States)

Akbar-Khanzadeh, Farhang; Milz, Sheryl A; Wagner, Cynthia D; Bisesi, Michael S; Ames, April L; Khuder, Sadik; Susi, Pam; Akbar-Khanzadeh, Mahboubeh

2010-12-01

Concrete grinding exposes workers to unacceptable levels of crystalline silica dust, known to cause diseases such as silicosis and possibly lung cancer. This study examined the influence of major factors of exposure and effectiveness of existing dust control methods by simulating field concrete grinding in an enclosed workplace laboratory. Air was monitored during 201 concrete grinding sessions while using a variety of grinders, accessories, and existing dust control methods, including general ventilation (GV), local exhaust ventilation (LEV), and wet grinding. Task-specific geometric mean (GM) of respirable crystalline silica dust concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled-grinding, while GV was off/on, were 0.17/0.09, 0.57/0.13, 1.11/0.44, and 23.1/6.80, respectively. Silica dust concentrations (mg/m³ using 100-125 mm (4-5 inch) and 180 mm (7 inch) grinding cups were 0.53/0.22 and 2.43/0.56, respectively. GM concentrations of silica dust were significantly lower for (1) GV on (66.0%) vs. off, and (2) LEV:HEPA- (99.0%), LEV:Shop-vac- (98.1%) or wet- (94.4%) vs. uncontrolled-grinding. Task-specific GM of respirable suspended particulate matter (RSP) concentrations (mg/m³ for LEV:HEPA-, LEV:Shop-vac-, wet-, and uncontrolled grinding, while GV was off/on, were 1.58/0.63, 7.20/1.15, 9.52/4.13, and 152/47.8, respectively. GM concentrations of RSP using 100-125 mm and 180 mm grinding cups were 4.78/1.62 and 22.2/5.06, respectively. GM concentrations of RSP were significantly lower for (1) GV on (70.2%) vs. off, and (2) LEV:HEPA- (98.9%), LEV:Shop-vac- (96.9%) or wet- (92.6%) vs. uncontrolled grinding. Silica dust and RSP were not significantly affected by (1) orientation of grinding surfaces (vertical vs. inclined); (2) water flow rates for wet grinding; (3) length of task-specific sampling time; or, (4) among cup sizes of 100, 115 or 125 mm. No combination of factors or control methods reduced an 8-hr exposure level to below the

42 CFR 84.1141 - Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

Science.gov (United States)

2010-10-01

... mist respirators designed for respiratory protection against fumes of various metals having an air... HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Dust, Fume, and Mist....1141 Isoamyl acetate tightness test; dust, fume, and mist respirators designed for respiratory...

Endotoxin and dust at respirable and nonrespirable particle sizes are not consistent between cage- and floor-housed poultry operations.

Science.gov (United States)

Kirychuk, Shelley P; Reynolds, Stephen J; Koehncke, Niels K; Lawson, Joshua; Willson, Philip; Senthilselvan, Ambikaipakan; Marciniuk, Darcy; Classen, Henry L; Crowe, Trever; Just, Natasha; Schneberger, David; Dosman, James A

2010-10-01

Individuals engaged in work in intensive animal houses experience some of the highest rates of occupationally related respiratory symptoms. Organic dust and in particular endotoxin has been most closely associated with respiratory symptoms and lung function changes in workers. It has previously been shown that for intensive poultry operations, type of poultry housing [cage-housed (CH) versus floor-housed (FH)] can influence the levels of environmental contaminants. The goal of the study was to determine the differences in endotoxin and dust levels at different size fractions between CH and FH poultry operations. Fifteen CH and 15 FH poultry operations were sampled for stationary measurements (area) of dust and associated endotoxin. Fractioned samples were collected utilizing Marple cascade impactors. Gravimetric and endotoxin analysis were conducted on each of the filters. When assessed by individual Marple stage, there was significantly greater airborne endotoxin concentration (endotoxin units per cubic meter) in the size fraction >9.8 μm for the FH operations whereas at the size fraction 1.6-3.5 μm, the CH operations had significantly greater airborne endotoxin concentration than the FH operations. Endotoxin concentration in the dust mass (endotoxin units per milligram) was significantly greater in the CH operations as compared to the FH operations for all size fractions >1.6 μm. As such, endotoxin in the respirable fraction accounted for 24% of the total endotoxin in the CH operations whereas it accounted for only 11% in the FH operations. There was significantly more dust in all size fractions in the FH operations as compared to the CH poultry operations. There is more endotoxin in the presence of significantly lower dust levels in the respirable particle size fractions in CH poultry operations as compared to the FH poultry operations. This difference in respirable endotoxin may be important in relation to the differential respiratory response experienced by

Relationships between Personal Measurements of 'Total' Dust, Respirable, Thoracic, and Inhalable Aerosol Fractions in the Cement Production Industry.

Science.gov (United States)

Notø, Hilde P; Nordby, Karl-Christian; Eduard, Wijnand

2016-05-01

The aims of this study were to examine the relationships and establish conversion factors between 'total' dust, respirable, thoracic, and inhalable aerosol fractions measured by parallel personal sampling on workers from the production departments of cement plants. 'Total' dust in this study refers to aerosol sampled by the closed face 37-mm Millipore filter cassette. Side-by-side personal measurements of 'total' dust and respirable, thoracic, and inhalable aerosol fractions were performed on workers in 17 European and Turkish cement plants. Simple linear and mixed model regressions were used to model the associations between the samplers. The total number of personal samples collected on 141 workers was 512. Of these 8.4% were excluded leaving 469 for statistical analysis. The different aerosol fractions contained from 90 to 130 measurements and-side-by side measurements of all four aerosol fractions were collected on 72 workers.The median ratios between observed results of the respirable, 'total' dust, and inhalable fractions relative to the thoracic aerosol fractions were 0.51, 2.4, and 5.9 respectively. The ratios between the samplers were not constant over the measured concentration range and were best described by regression models. Job type, position of samplers on left or right shoulder and plant had no substantial effect on the ratios. The ratios between aerosol fractions changed with different air concentrations. Conversion models for estimation of the fractions were established. These models explained a high proportion of the variance (74-91%) indicating that they are useful for the estimation of concentrations based on measurements of a different aerosol fraction. The calculated uncertainties at most observed concentrations were below 30% which is acceptable for comparison with limit values (EN 482, 2012). The cement industry will therefore be able to predict the health related aerosol fractions from their former or future measurements of one of the

Assessment of respirable dust and its free silica contents in different Indian coalmines.

Science.gov (United States)

Mukherjee, Ashit K; Bhattacharya, Sanat K; Saiyed, Habibullah N

2005-04-01

Assessment of respirable dust, personal exposures of miners and free silica contents in dust were undertaken to find out the associated risk of coal workers' pneumoconiosis in 9 coal mines of Eastern India during 1988-91. Mine Research Establishment (MRE), 113A Gravimetric Dust Sampler (GDS) and personal samplers (AFC 123), Cassella, London, approved by Director General of Mines Safety (DGMS) were used respectively for monitoring of mine air dust and personal exposures of miners. Fourier Transform Infra-red (FTIR) Spectroscopy determined free silica in respirable dusts. Thermal Conditions like Wet Bulb Globe Temperature (WBGT) index, humidity and wind velocity were also recorded during monitoring. The dust levels in the face return air of both, Board & Pillar (B&P) and Long Wall (LW) mining were found above the permissible level recommended by DGMS, Govt. of India. The drilling, blasting and loading are the major dusty operations in B&P method. Exposures of driller and loader were varied between, 0.81-9.48 mg/m3 and 0.05-9.84 mg/m3 respectively in B&P mining, whereas exposures of DOSCO loader, Shearer operator and Power Support Face Worker were varied between 2.65-9.11 mg/m3, 0.22-10.00 mg/m3 and 0.12-9.32 mg/m3 respectively in LW mining. In open cast mining, compressor and driller operators are the major exposed groups. The percentage silica in respirable dusts found below 5% in all most all the workers except among query loaders and drillers of open cast mines.

Respirable dust and quartz exposure from three South African farms with sandy, sandy loam, and clay soils.

Science.gov (United States)

Swanepoel, Andrew J; Kromhout, Hans; Jinnah, Zubair A; Portengen, Lützen; Renton, Kevin; Gardiner, Kerry; Rees, David

2011-07-01

To quantify personal time-weighted average respirable dust and quartz exposure on a sandy, a sandy loam, and a clay soil farm in the Free State and North West provinces of South Africa and to ascertain whether soil type is a determinant of exposure to respirable quartz. Three farms, located in the Free State and North West provinces of South Africa, had their soil type confirmed as sandy, sandy loam, and clay; and, from these, a total of 298 respirable dust and respirable quartz measurements were collected between July 2006-November 2009 during periods of major farming operations. Values below the limit of detection (LOD) (22 μg · m(-3)) were estimated using multiple 'imputation'. Non-parametric tests were used to compare quartz exposure from the three different soil types. Exposure to respirable quartz occurred on all three farms with the highest individual concentration measured on the sandy soil farm (626 μg · m(-3)). Fifty-seven, 59, and 81% of the measurements on the sandy soil, sandy loam soil, and clay soil farm, respectively, exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 25 μg · m(-3). Twelve and 13% of respirable quartz concentrations exceeded 100 μg · m(-3) on the sandy soil and sandy loam soil farms, respectively, but none exceeded this level on the clay soil farm. The proportions of measurements >100 μg · m(-3) were not significantly different between the sandy and sandy loam soil farms ('prop.test'; P = 0.65), but both were significantly larger than for the clay soil farm ('prop.test'; P = 0.0001). The percentage of quartz in respirable dust was determined for all three farms using measurements > the limit of detection. Percentages ranged from 0.5 to 94.4% with no significant difference in the median quartz percentages across the three farms (Kruskal-Wallis test; P = 0.91). This study demonstrates that there is significant potential for over-exposure to respirable quartz in

30 CFR 90.209 - Respirable dust samples; transmission by operator.

Science.gov (United States)

2010-07-01

... LABOR COAL MINE SAFETY AND HEALTH MANDATORY HEALTH STANDARDS-COAL MINERS WHO HAVE EVIDENCE OF THE DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.209 Respirable dust samples; transmission by operator. (a) The operator shall transmit within 24 hours after the end of the sampling shift all samples...

75 FR 64411 - Lowering Miners' Exposure to Respirable Coal Mine Dust, Including Continuous Personal Dust Monitors

Science.gov (United States)

2010-10-19

... industries, such as mining, by reducing workplace deaths and improving the health of coal miners. This..., enhanced enforcement, collaborative outreach, and education and training. The initiative will reduce, and... reducing the respirable coal mine dust levels, miners continue to develop black lung. Based on recent data...

77 FR 38323 - Proposed Extension of Existing Information Collection; Respirable Coal Mine Dust Sampling

Science.gov (United States)

2012-06-27

... Information Collection; Respirable Coal Mine Dust Sampling AGENCY: Mine Safety and Health Administration... Sampling'' to more accurately reflect the type of information that is collected. Chronic exposure to... dust levels since 1970 and, consequently, the prevalence rate of black lung among coal miners, severe...

Exposure to respirable dust and crystalline silica in bricklaying education at Dutch vocational training centers.

NARCIS (Netherlands)

Huizer, D.; Spee, T.; Lumens, M.E.G.L.; Kromhout, H.

2010-01-01

BACKGROUND: Construction workers are educated at vocational training centers before they begin their working lives. Future bricklayers and their instructors are exposed to respirable dust and possibly to hazardous respirable crystalline silica from trial mortar. METHODS: Thirty-six personal air

30 CFR 90.210 - Respirable dust samples; report to operator.

Science.gov (United States)

2010-07-01

... MINE SAFETY AND HEALTH MANDATORY HEALTH STANDARDS-COAL MINERS WHO HAVE EVIDENCE OF THE DEVELOPMENT OF PNEUMOCONIOSIS Sampling Procedures § 90.210 Respirable dust samples; report to operator. (a) The Secretary shall... for voiding any samples; and, (7) The Social Security Number of the part 90 miner. (b) Upon receipt...

Research and development in dust and silicosis suppression

Energy Technology Data Exchange (ETDEWEB)

Breuer, H

1975-08-21

MAK values of 4 mg/m/sup 3/ for respirable dust containing quartz and 0.15 mg/m/sup 3/ for respirable quartz dust have been established for 5 years' exposure in West German hard coal mines. Routine gravimetric measurements were introduced in 1974 and these are supplemented by the digital Tyndallometer which indicates short-term variations. Gravimetric measurements have indicated the main sources of dust and improved dust suppression measures have considerably reduced respirable dust concentrations in some cases, e.g., by seam infusion, by spraying of the face machine path and at crushers, and by dedusters on heading machines.

The Effects of Bit Wear on Respirable Silica Dust, Noise and Productivity: A Hammer Drill Bench Study.

Science.gov (United States)

Carty, Paul; Cooper, Michael R; Barr, Alan; Neitzel, Richard L; Balmes, John; Rempel, David

2017-07-01

Hammer drills are used extensively in commercial construction for drilling into concrete for tasks including rebar installation for structural upgrades and anchor bolt installation. This drilling task can expose workers to respirable silica dust and noise. The aim of this pilot study was to evaluate the effects of bit wear on respirable silica dust, noise, and drilling productivity. Test bits were worn to three states by drilling consecutive holes to different cumulative drilling depths: 0, 780, and 1560 cm. Each state of bit wear was evaluated by three trials (nine trials total). For each trial, an automated laboratory test bench system drilled 41 holes 1.3 cm diameter, and 10 cm deep into concrete block at a rate of one hole per minute using a commercially available hammer drill and masonry bits. During each trial, dust was continuously captured by two respirable and one inhalable sampling trains and noise was sampled with a noise dosimeter. The room was thoroughly cleaned between trials. When comparing results for the sharp (0 cm) versus dull bit (1560 cm), the mean respirable silica increased from 0.41 to 0.74 mg m-3 in sampler 1 (P = 0.012) and from 0.41 to 0.89 mg m-3 in sampler 2 (P = 0.024); levels above the NIOSH recommended exposure limit of 0.05 mg m-3. Likewise, mean noise levels increased from 112.8 to 114.4 dBA (P < 0.00001). Drilling productivity declined with increasing wear from 10.16 to 7.76 mm s-1 (P < 0.00001). Increasing bit wear was associated with increasing respirable silica dust and noise and reduced drilling productivity. The levels of dust and noise produced by these experimental conditions would require dust capture, hearing protection, and possibly respiratory protection. The findings support the adoption of a bit replacement program by construction contractors. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

[Dust concentration analysis in non-coal mining. Exposure evaluation based on measurements performed by occupational hygiene laboratories in the years 2001-2005 in Poland].

Science.gov (United States)

Bujak-Pietrek, Stella; Mikołajczyk, Urszula; Szadkowska-Stańczyk, Irena

2011-01-01

Non-coal mining includes the extraction of materials for construction (stone, gravel, sand and clay), chemical industry (salt and sulfur), metallurgy (metal ores, uranium and thorium) and other mining and quarrying. Regardless of the type of mining company one of the most common health hazards in this sector is exposure to high concentrations of dust occurring during the extraction of materials. Such activities as drilling, use of blasting agents, processing of raw material, its transportation and loading are the source of large amounts of dust containing crystalline silica. Data on exposure to dust, collected by industrial hygiene laboratories on the basis of dust concentration measurements in the work environment, were obtained from the sanitary inspection service. The analysis of dust concentrations at workplaces in non-coal mining covered the years 2001-2005. The average concentration of inhalable and respirable dust and the degree of results dispersion at workposts in different branches of non-coal mining (according to NACE rev1.1) were evaluated. Also there was estimated the percentage of surveys indicating dust concentrations above hygiene standards. Almost 5000 measurements of dust concentrations were performed in the years under study. The highest concentration of inhalable dust was noted for the production of salt (5.51 mg/m3), other mining and quarrying (4.30 mg/m3) and quarrying of slate (3.77 mg/m3). For respirable dust the highest concentrations were noted in other mining and quarrying (1.10 mg/m3), quarrying of slate (1.09 mg/m3) and quarrying of stone (0.81 mg/m3). Exposure to high concentrations of dust during the extraction of non-carbon is still an important hazard to human health. Almost for all workposts under study the excess of hygiene standards were observed.

Control of dust hazards in mines

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, V V

1981-09-01

This paper analyzes health hazards associated with air pollution by respirable coal dust which causes pneumoconioses. The following directions in pneumoconioses prevention are discussed: improved protective systems (e.g. respirators), mining schemes optimized from a health hazards point of view, correct determination of the maximum permissible level of respirable dusts, reducing working time. Safety regulations in the USSR on the critical amount of coal dust in the miner respiratory system are insufficient as the 20 g limit is too high and does not guarantee safety. Using regression analysis influence of the factors which cause pneumoconioses is analyzed. This influence is described by an equation which considers the following factors: number of shifts associated with contact of a miner with coal dusts, dust concentration in mine air, amount of air with coal dust being respirated, miner's age, years as miner, coal rank. It is stated that use of the proposed equation (derived by computer calculations) permits the safe working time to be correctly determined considering all factors which cause pneumoconioses.

Filter penetration and breathing resistance evaluation of respirators and dust masks.

Science.gov (United States)

Ramirez, Joel; O'Shaughnessy, Patrick

2017-02-01

The primary objective of this study was to compare the filter performance of a representative selection of uncertified dust masks relative to the filter performance of a set of NIOSH-approved N95 filtering face-piece respirators (FFRs). Five different models of commercially available dust masks were selected for this study. Filter penetration of new dust masks was evaluated against a sodium chloride aerosol. Breathing resistance (BR) of new dust masks and FFRs was then measured for 120 min while challenging the dust masks and FFRs with Arizona road dust (ARD) at 25°C and 30% relative humidity. Results demonstrated that a wide range of maximum filter penetration was observed among the dust masks tested in this study (3-75% at the most penetrating particle size (p masks did not vary greatly (8-13 mm H 2 O) but were significantly different (p mask. Microscopic analysis of the external layer of each dust mask and FFR suggests that different collection media in the external layer influences the development of the dust layer and therefore affects the increase in BR differently between the tested models. Two of the dust masks had penetration values masks, those with penetration > 15%, had quality factors ranging between 0.04-0.15 primarily because their initial BR remained relatively high. These results indicate that some dust masks analysed during this research did not have an expected very low BR to compensate for their high penetration.

Indoor and ambient air concentrations of respirable particles between two hospitals in Kashan (2014-2015

Directory of Open Access Journals (Sweden)

Mahmoud Mohammadyan

2017-04-01

Full Text Available Background: The hospital environment requires special attention to provide healthful indoor air quality for protecting patients and healthcare workers against the occupational diseases. The aim of this study was to determine the concentrations of respirable particles indoor and ambient air of two hospitals in Kashan. Materials and Method: This cross-sectional study was conducted during 3 months (Marth 2014 to May 2015. Indoor and outdoor PM10 and PM2.5 concentrations were measured four times a week in the operating room, pediatric and ICU2 (Intensive Care Unit wards using a real time dust monitor at two hospitals. A total number of 480 samples (80 samples indoors and 40 outdoors from wards were collected. Results: The highest mean PM2.5 and PM10 for indoors were determined 57.61± 68.57 µg m-3 and 212.36±295.49 µg m-3, respectively. The results showed a significant relationship between PM2.5 and PM10 in the indoor and ambient air of two hospitals (P<0.05. PM2.5 and PM10 concentrations were different in all of the selected wards (P<0.05. Conclusion: The respirable particle concentrations in the indoor and ambient air in both hospitals were higher than the 24-hours WHO and US-EPA standards. Thence, utilizing sufficient and efficient air conditioning systems in hospitals can be useful in improving indoor air quality and reducing the respirable particle concentrations.

Exposure to dust and its particle size distribution in shoe manufacture and repair workplaces measured with GRIMM laser dust monitor.

Science.gov (United States)

Stroszejn-Mrowca, Grazyna; Szadkowska-Stańczyk, Irena

2003-01-01

Owing to a diversified technological process and a great variety of products and materials used in shoe manufacture, workers may be exposed to dusts that contain different chemicals and particles of various shapes and sizes. The aim of this study was to assess the dust exposure, taking account of concentration of particular size fractions according to the European Standard Norm, and to analyze particle size distribution in inhalable dust at selected workplaces in a modern shoe manufacture plant and in a small shoe repair workshop in comparison with other industrial branches. In these two workplaces, the concentrations of dust, representing the inhalable, thoracic, and respirable fractions, were measured with the GRIMM 1.105 laser dust monitor. The particle size distribution in inhaled dust in the most characteristic workposts was analyzed. In the shoe manufacture plant, the concentrations ranged from 124 microg/m3 (leather cutting out) to 724 microg/m3 (scouring and milling of soles); concentrations of the thoracic and respirable fractions in the same workposts ranged from 74 microg/m3 to 412 microg/m3 and from 24 microg/m3 to 120 microg/m3, respectively. In the shoe repair workshop, the recorded concentrations were higher: the values ranged from 521 microg/m3 (gluing of shoes and soles, zipper exchange and heel abrasion) to 916 microg/m3 (uppers sewing and heel scouring) for the inhaled fraction; from 335 microg/m3 to 499 microg/m3 for the thoracic fraction; and from 88 microg/m3 to 120 microg/m3 for the respirable fraction. The mass median aerodynamic diameters of inhalable dust particles fell within the limits of 6.2-25.0 mm. Dust with the smallest particles (MMAD = 6.2 mm) was observed in shoe brushing and polishing, and with the largest particles (MMAD = 25.0 mm) in uppers sewing. The modern process of shoe manufacture is characterized by very low concentrations of inhalable dust and its fractions, they are considerably lower than occupational exposure limits

Radiation dose to workers due to the inhalation of dust during granite fabrication

International Nuclear Information System (INIS)

Zwack, L M; Stewart, J H; McCarthy, J F; Allen, J G; McCarthy, W B

2014-01-01

There has been very little research conducted to determine internal radiation doses resulting from worker exposure to ionising radiation in granite fabrication shops. To address this issue, we estimated the effective radiation dose of granite workers in US fabrication shops who were exposed to the maximum respirable dust and silica concentrations allowed under current US regulations, and also to concentrations reported in the literature. Radiation doses were calculated using standard methods developed by the International Commission on Radiological Protection. The calculated internal doses were very low, and below both US occupational standards (50 mSv yr −1 ) and limits applicable to the general public (1 mSv yr −1 ). Workers exposed to respirable granite dust concentrations at the US Occupational Safety and Health Administration (OSHA) respirable dust permissible exposure limit (PEL) of 5 mg m −3 over a full year had an estimated radiation dose of 0.062 mSv yr −1 . Workers exposed to respirable granite dust concentrations at the OSHA silica PEL and at the American Conference of Governmental Industrial Hygienists Threshold Limit Value for a full year had expected radiation doses of 0.007 mSv yr −1 and 0.002 mSv yr −1 , respectively. Using data from studies of respirable granite dust and silica concentrations measured in granite fabrication shops, we calculated median expected radiation doses that ranged from <0.001 to 0.101 mSv yr −1 . (paper)

Dust exposure and pneumoconiosis in a South African pottery. 1. Study objectives and dust exposure.

Science.gov (United States)

Rees, D; Cronje, R; du Toit, R S

1992-07-01

Dust exposure and pneumoconiosis were investigated in a South African pottery that manufactured wall tiles and bathroom fittings. This paper describes the objectives of the investigation and presents dust measurement data. x Ray diffraction showed that the clays used by the pottery had a high quartz content (range 58%-23%, mean 38%). Exposure to respirable dust was measured for 43 workers and was highest (6.6 mg/m3) in a bathroom fitting fettler. Quartz concentrations in excess of 0.1 mg/m3 were found in all sections of the manufacturing process from slip production to biscuit firing and sorting. The proportion of quartz in the respirable dust of these sections was 24% to 33%. This is higher than is usually reported in English potteries. Four hundred and six (80%) of the 509 workers employed at the pottery were potentially at risk of occupational lung disease. The finding of large numbers of pottery workers exposed to unacceptable dust concentrations is not surprising as poor dust control was found in all six wall tile and sanitary ware factories surveyed by the National Centre for Occupational Health between 1973 and 1989. Dust related occupational disease can be expected in potters for many years to come.

Measurement of respirable superabsorbent polyacrylate (SAP) dust by ethanol derivatization using gas chromatography-mass spectrometry (GC-MS) detection.

Science.gov (United States)

McCormack, Paul; Lemmo, John S; Macomber, Margaret; Holcomb, Mark L; Lieckfield, Robert

2011-04-01

Superabsorbent polyacrylate (SAP) is an important industrial chemical manufactured primarily as sodium polyacrylate but occasionally as potassium salt. It has many applications owing to its intrinsic physical property of very high water absorption, which can be more than 100 times it own weight. SAP is commonly used in disposable diapers and feminine hygiene products and is known by a number of synonyms-sodium polyacrylate, superabsorbent polyacrylate (SAP), polyacrylate absorbent (PA), and superabsorbent material (SAM). Germany and The Netherlands have adopted a nonbinding scientific guideline value 0.05 mg/m³ (8-hr time-weighted average, TWA) as the maximum allowable workplace concentration for the respirable dust of SAP (acrylate was developed and validated for the analysis of respirable superabsorbent polyacrylate dust collected on filter cassettes in the workplace environment. This method is an alternative to the commonly used sodium-based method, which is limited owing to potential interference by other sources of sodium from the workplace and laboratory environments. The alcohol derivatization method effectively eliminates sodium interference from several classes of sodium compounds, as shown by their purposeful introduction at two and six times the equivalent amount of SAP present in reference samples. The accuracy of the method, as determined by comparison with sodium analysis of known reference samples, was greater than 80% over the study range of 5-50 μg of SAP dust. The lower reporting limit of the method is 3.0 μg of SAP per sample, which is equivalent to 3 (μg/m³) for an 8-hr sampling period at the recommended flow rate of 2.2 L/min.

Exposure to dust and particle-associated 1-nitropyrene of drivers of diesel-powered equipment in underground mining.

Science.gov (United States)

Scheepers, P T J; Micka, V; Muzyka, V; Anzion, R; Dahmann, D; Poole, J; Bos, R P

2003-07-01

A field study was conducted in two mines in order to determine the most suitable strategy for ambient exposure assessment in the framework of a European study aimed at validation of biological monitoring approaches for diesel exhaust (BIOMODEM). Exposure to dust and particle-associated 1-nitropyrene (1-NP) was studied in 20 miners of black coal by the long wall method (Czech Republic) and in 20 workers in oil shale mining by the room and pillar method (Estonia). The study in the oil shale mine was extended to include 100 workers in a second phase (main study). In each mine half of the study population worked underground as drivers of diesel-powered trains (black coal) and excavators (oil shale). The other half consisted of workers occupied in various non-diesel production assignments. Exposure to diesel exhaust was studied by measurement of inhalable and respirable dust at fixed locations and by personal air sampling of respirable dust. The ratio of geometric mean inhalable to respirable dust concentration was approximately two to one. The underground/surface ratio of respirable dust concentrations measured at fixed locations and in the breathing zones of the workers was 2-fold or greater. Respirable dust was 2- to 3-fold higher in the breathing zone than at fixed sampling locations. The 1-NP content in these dust fractions was determined by gas chromatography-mass spectrometry/mass spectrometry and ranged from 0.003 to 42.2 ng/m(3) in the breathing zones of the workers. In mine dust no 1-NP was detected. In both mines 1-NP was observed to be primarily associated with respirable particles. The 1-NP concentrations were also higher underground than on the surface (2- to 3-fold in the coal mine and 10-fold or more in the oil shale mine). Concentrations of 1-NP in the breathing zones were also higher than at fixed sites (2.5-fold in the coal mine and 10-fold in the oil shale mine). For individual exposure assessment personal air sampling is preferred over air sampling

15 years of monitoring occupational exposure to respirable dust and quartz within the European industrial minerals sector.

Science.gov (United States)

Zilaout, Hicham; Vlaanderen, Jelle; Houba, Remko; Kromhout, Hans

2017-07-01

In 2000, a prospective Dust Monitoring Program (DMP) was started in which measurements of worker's exposure to respirable dust and quartz are collected in member companies from the European Industrial Minerals Association (IMA-Europe). After 15 years, the resulting IMA-DMP database allows a detailed overview of exposure levels of respirable dust and quartz over time within this industrial sector. Our aim is to describe the IMA-DMP and the current state of the corresponding database which due to continuation of the IMA-DMP is still growing. The future use of the database will also be highlighted including its utility for the industrial minerals producing sector. Exposure data are being obtained following a common protocol including a standardized sampling strategy, standardized sampling and analytical methods and a data management system. Following strict quality control procedures, exposure data are consequently added to a central database. The data comprises personal exposure measurements including auxiliary information on work and other conditions during sampling. Currently, the IMA-DMP database consists of almost 28,000 personal measurements which have been performed from 2000 until 2015 representing 29 half-yearly sampling campaigns. The exposure data have been collected from 160 different worksites owned by 35 industrial mineral companies and comes from 23 European countries and approximately 5000 workers. The IMA-DMP database provides the European minerals sector with reliable data regarding worker personal exposures to respirable dust and quartz. The database can be used as a powerful tool to address outstanding scientific issues on long-term exposure trends and exposure variability, and importantly, as a surveillance tool to evaluate exposure control measures. The database will be valuable for future epidemiological studies on respiratory health effects and will allow for estimation of quantitative exposure response relationships. Copyright © 2017 The

Assessment of occupational exposure to wood dust in the Polish furniture industry

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Małgorzata Szewczyńska

2017-02-01

Full Text Available Background: Occupational exposure to wood dust can be responsible for many different harmful health effects, especially in workers employed in the wood industry. The assessment of wood dust adverse effects to humans, as well as the interpretation of its concentration measurements carried out to assess potential occupational exposure are very difficult. First of all, it is due to possible occurrence of different kind of wood dust in the workplace air, namely wood dust from dozens of species of trees belonging to 2 kinds of botanical gymnosperms and angiosperms, as well as to its different chemical composition. Material and Methods: Total dust and respirable wood dust in the workplace air in the furniture industry was determined using the filtration-gravimetric method in accordance with Polish Standards PN-Z-04030-05:1991 and PN-Z-04030-06:1991. Air samples were collected based on the principles of individual dosimetry. Results: Total dust concentrations were 0.84–13.92 mg/m3 and inhalable fraction concentrations, obtained after the conversion of total dust by applying a conversion factor of 1.59, were 1.34–22.13 mg/m3. Respirable fraction concentrations were 0.38–4.04 mg/m3, which makes approx. 25% of the inhalable fraction on average. The highest concentrations occurred in grinding and the lowest during milling processes of materials used in the manufacture of furniture. Conclusions: The results indicate that the share of respirable fraction in the inhalable fraction of wood dust is considerable. Due to the determination of the threshold limit value (TLV for the inhalable fraction of wood dust, it is necessary to replace the previously used samplers for total dust with samplers that provide quantitative separation of wood dust inhalable fractions in accordance with the convention of this fraction as defined in PN-EN 481:1998. Med Pr 2017;68(1:45–60

[Assessment of occupational exposure to wood dust in the Polish furniture industry].

Science.gov (United States)

Szewczyńska, Małgorzata; Pośniak, Małgorzata

2017-02-28

Occupational exposure to wood dust can be responsible for many different harmful health effects, especially in workers employed in the wood industry. The assessment of wood dust adverse effects to humans, as well as the interpretation of its concentration measurements carried out to assess potential occupational exposure are very difficult. First of all, it is due to possible occurrence of different kind of wood dust in the workplace air, namely wood dust from dozens of species of trees belonging to 2 kinds of botanical gymnosperms and angiosperms, as well as to its different chemical composition. Total dust and respirable wood dust in the workplace air in the furniture industry was determined using the filtration-gravimetric method in accordance with Polish Standards PN-Z-04030-05:1991 and PN-Z-04030-06:1991. Air samples were collected based on the principles of individual dosimetry. Total dust concentrations were 0.84-13.92 mg/m3 and inhalable fraction concentrations, obtained after the conversion of total dust by applying a conversion factor of 1.59, were 1.34-22.13 mg/m3. Respirable fraction concentrations were 0.38-4.04 mg/m3, which makes approx. 25% of the inhalable fraction on average. The highest concentrations occurred in grinding and the lowest during milling processes of materials used in the manufacture of furniture. The results indicate that the share of respirable fraction in the inhalable fraction of wood dust is considerable. Due to the determination of the threshold limit value (TLV) for the inhalable fraction of wood dust, it is necessary to replace the previously used samplers for total dust with samplers that provide quantitative separation of wood dust inhalable fractions in accordance with the convention of this fraction as defined in PN-EN 481:1998. Med Pr 2017;68(1):45-60. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Determination of exposure to respirable quartz in the stone crushing units at Azendarian-West of Iran.

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Bahrami, Abdul Rahman; Golbabai, Faridah; Mahjub, Hossien; Qorbani, Farshid; Aliabadi, Mohsan; Barqi, Mohamadali

2008-08-01

The purpose of this study is to describe the personal exposure to respirable dust and quartz and in stone crushing units located at west of Iran. A size of 40 personal samples and 40 stationary samples were obtained and analysis was done by X-ray diffraction (XRD). The results of personal sampling were shown the concentrations of respirable dust exposure level in workers of process, hopper and drivers were 1.90, 2.22, 1.41 times greater than Occupational Safety and Health Administration permissible exposure limit (OSHA PEL). The average value of total dust and respirable dust emission from stationary sources was 9.46 mg/m(3), 1.24 mg/m(3) respectively, showing that 13.8 % of total dust is respirable. The efficiency of local exhaust ventilation (LEV) to control of particles inside of industrial units was greater than 99%. It is concluded from this research the particulate generated from stone crushing activities contain a significant amount of respirable particle. The amount of free silica in stone quartz is 85 to 97 percent that emission of particles effect to health workers. LEV has important effect in the removal of silica particles in stone crushing units. The worker of hoppers still exposed to silica more than standard limits.

Electronic design of air dust concentration gauge

International Nuclear Information System (INIS)

Machaj, B.; Strzalkowski, J.; Krawczynska, B.

1993-01-01

A new version of isotope dust concentration gauge for monitoring airborne dust pollution of air employs a ready made personal computer as the control and processing unit in the gauge instead of specialized electronics. That solution of the gauge reduces the needed specialized electronics to a simple computer interface coupling the computer to the measuring head. This also reduced electronics of the measuring head itself, i.e. GM detector circuit, power supplies and electronic circuits to switch on/off driving motors. The functioning and operation of the gauge is controlled by the computer program that can be easily modified if needed. The computer program for the gauge enables automatic measurements of dust concentration. Up to fifty measuring cycles can be easily programmed for a day. The results of measurements are presented in the form of data collection, diagram of dust concentration distribution during one day, diagram of dust distribution during 30 successive days or diagram of average dust concentration distribution during a day which may be computed by combining data of the selected number of measurements. Recalibration of the gauge and checking up of the gauge are also carried out under the program control. (author). 6 refs, 9 figs

77 FR 59667 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Respirable...

Science.gov (United States)

2012-09-28

... operator to protect miners from exposure to excessive dust levels. The respirable coal mine dust sampling... for OMB Review; Comment Request; Respirable Coal Mine Dust Sampling ACTION: Notice. SUMMARY: The... information collection request (ICR) titled, ``Respirable Coal Mine Dust Sampling,'' to the Office of...

30 CFR 90.301 - Respirable dust control plan; approval by District Manager; copy to part 90 miner.

Science.gov (United States)

2010-07-01

... District Manager; copy to part 90 miner. 90.301 Section 90.301 Mineral Resources MINE SAFETY AND HEALTH... control plan; approval by District Manager; copy to part 90 miner. (a) The District Manager will approve... District Manager shall consider whether: (1) The respirable dust control measures would be likely to...

Aquatic respiration rate measurements at low oxygen concentrations.

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Moritz Holtappels

Full Text Available Despite its huge ecological importance, microbial oxygen respiration in pelagic waters is little studied, primarily due to methodological difficulties. Respiration measurements are challenging because of the required high resolution of oxygen concentration measurements. Recent improvements in oxygen sensing techniques bear great potential to overcome these limitations. Here we compare 3 different methods to measure oxygen consumption rates at low oxygen concentrations, utilizing amperometric Clark type sensors (STOX, optical sensors (optodes, and mass spectrometry in combination with (18-18O2 labeling. Oxygen concentrations and consumption rates agreed well between the different methods when applied in the same experimental setting. Oxygen consumption rates between 30 and 400 nmol L(-1 h(-1 were measured with high precision and relative standard errors of less than 3%. Rate detection limits in the range of 1 nmol L(-1 h(-1 were suitable for rate determinations in open ocean water and were lowest at the lowest applied O2 concentration.

Real-time measurement of dust in the workplace using video exposure monitoring: Farming to pharmaceuticals

International Nuclear Information System (INIS)

Walsh, P T; Forth, A R; Clark, R D R; Dowker, K P; Thorpe, A

2009-01-01

Real-time, photometric, portable dust monitors have been employed for video exposure monitoring (VEM) to measure and highlight dust levels generated by work activities, illustrate dust control techniques, and demonstrate good practice. Two workplaces, presenting different challenges for measurement, were used to illustrate the capabilities of VEM: (a) poultry farming activities and (b) powder transfer operations in a pharmaceutical company. For the poultry farm work, the real-time monitors were calibrated with respect to the respirable and inhalable dust concentrations using cyclone and IOM reference samplers respectively. Different rankings of exposure for typical activities were found on the small farm studied here compared to previous exposure measurements at larger poultry farms: these were mainly attributed to the different scales of operation. Large variations in the ratios of respirable, inhalable and real-time monitor TWA concentrations of poultry farm dust for various activities were found. This has implications for the calibration of light-scattering dust monitors with respect to inhalable dust concentration. In the pharmaceutical application, the effectiveness of a curtain barrier for dust control when dispensing powder in a downflow booth was rapidly demonstrated.

Sulfide-inhibition of mitochondrial respiration at very low oxygen concentrations.

Science.gov (United States)

Matallo, J; Vogt, J; McCook, O; Wachter, U; Tillmans, F; Groeger, M; Szabo, C; Georgieff, M; Radermacher, P; Calzia, E

2014-09-15

Our aim was to study the ability of an immortalized cell line (AMJ2-C11) to sustain aerobic cell respiration at decreasing oxygen concentrations under continuous sulfide exposure. We assumed that the rate of elimination of sulfide through the pathway linked to the mitochondrial respiratory chain and therefore operating under aerobic conditions, should decrease with limiting oxygen concentrations. Thus, sulfide's inhibition of cellular respiration would occur faster under continuous sulfide exposure when the oxygen concentration is in the very low range. The experiments were performed with an O2K-oxygraph (Oroboros Instruments) by suspending 0.5-1×10(6) cells in 2 ml of continuously stirred respiration medium at 37 °C and calculating the oxygen flux (JO2) as the negative derivative of the oxygen concentration in the medium. The cells were studied in two different metabolic states, namely under normal physiologic respiration (1) and after uncoupling of mitochondrial respiration (2). Oxygen concentration was controlled by means of a titration-injection pump, resulting in average concentration values of 0.73±0.05 μM, 3.1±0.2 μM, and 6.2±0.2 μM. Simultaneously we injected a 2 mM Na2S solution at a continuous rate of 10 μl/s in order to quantify the titration-time required to reduce the JO2 to 50% of the initial respiratory activity. Under the lowest oxygen concentration this effect was achieved after 3.5 [0.3;3.5] and 11.7 [6.2;21.2]min in the uncoupled and coupled state, respectively. This time was statistically significantly shorter when compared to the intermediate and the highest O2 concentrations tested, which yielded values of 24.6 [15.5;28.1]min (coupled) and 35.9 [27.4;59.2]min (uncoupled), as well as 42.4 [27.5;42.4]min (coupled) and 51.5 [46.4;51.7]min (uncoupled). All data are medians [25%, and 75% percentiles]. Our results confirm that the onset of inhibition of cell respiration by sulfide occurs earlier under a continuous exposure when approaching

The Spatial Variation of Dust Particulate Matter Concentrations during Two Icelandic Dust Storms in 2015

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Pavla Dagsson-Waldhauserova

2016-06-01

Full Text Available Particulate matter mass concentrations and size fractions of PM1, PM2.5, PM4, PM10, and PM15 measured in transversal horizontal profile of two dust storms in southwestern Iceland are presented. Images from a camera network were used to estimate the visibility and spatial extent of measured dust events. Numerical simulations were used to calculate the total dust flux from the sources as 180,000 and 280,000 tons for each storm. The mean PM15 concentrations inside of the dust plumes varied from 10 to 1600 µg·m−3 (PM10 = 7 to 583 µg·m−3. The mean PM1 concentrations were 97–241 µg·m−3 with a maximum of 261 µg·m−3 for the first storm. The PM1/PM2.5 ratios of >0.9 and PM1/PM10 ratios of 0.34–0.63 show that suspension of volcanic materials in Iceland causes air pollution with extremely high PM1 concentrations, similar to polluted urban areas in Europe or Asia. Icelandic volcanic dust consists of a higher proportion of submicron particles compared to crustal dust. Both dust storms occurred in relatively densely inhabited areas of Iceland. First results on size partitioning of Icelandic dust presented here should challenge health authorities to enhance research in relation to dust and shows the need for public dust warning systems.

Dust exposure in workers from grain storage facilities in Costa Rica.

Science.gov (United States)

Rodríguez-Zamora, María G; Medina-Escobar, Lourdes; Mora, Glend; Zock, Jan-Paul; van Wendel de Joode, Berna; Mora, Ana M

2017-08-01

About 12 million workers are involved in the production of basic grains in Central America. However, few studies in the region have examined the occupational factors associated with inhalable dust exposure. (i) To assess the exposure to inhalable dust in workers from rice, maize, and wheat storage facilities in Costa Rica; (ii) to examine the occupational factors associated with this exposure; and (iii) to measure concentrations of respirable and thoracic particles in different areas of the storage facilities. We measured inhalable (dust concentrations in 176 personal samples collected from 136 workers of eight grain storage facilities in Costa Rica. We also measured respirable (dust particles in several areas of the storage facilities. Geometric mean (GM) and geometric standard deviation (GSD) inhalable dust concentrations were 2.0mg/m 3 and 7.8 (range=dust concentrations were associated with job category [GM for category/GM for administrative staff and other workers (95% CI)=4.4 (2.6, 7.2) for packing; 20.4 (12.3, 34.7) for dehulling; 109.6 (50.1, 234.4) for unloading in flat bed sheds; 24.0 (14.5, 39.8) for unloading in pits; and 31.6 (18.6, 52.5) for drying], and cleaning task [15.8 (95% CI: 10.0, 26.3) in workers who cleaned in addition to their regular tasks]. Higher area concentrations of thoracic dust particles were found in wheat (GM and GSD=4.3mg/m 3 and 4.5) and maize (3.0mg/m 3 and 3.9) storage facilities, and in grain drying (2.3mg/m 3 and 3.1) and unloading (1.5mg/m 3 and 4.8) areas. Operators of grain storage facilities showed elevated inhalable dust concentrations, mostly above international exposure limits. Better engineering and administrative controls are needed. Copyright © 2017 Elsevier GmbH. All rights reserved.

Dust in Snow in the Colorado River Basin: Spatial Variability in Dust Concentrations, Radiative Forcing, and Snowmelt Rates

Science.gov (United States)

Skiles, M.; Painter, T.; Deems, J. S.; Landry, C.; Bryant, A.

2012-12-01

Since the disturbance of the western US that began with the Anglo settlement in the mid 19th century, the mountain snow cover of the Colorado River Basin (CRB) has been subject to five-fold greater dust loading. This dust deposition accelerates snowmelt through its direct reduction of albedo and its further reduction of albedo by accelerating the growth of snow effective grain size. We have previously quantified the impacts of dust in snow using a 6-year record of dust concentration and energy balance fluxes at the alpine and subalpine towers in the Senator Beck Basin Study Area (SBBSA), San Juan Mountains in southwestern Colorado, USA. Dust loading exhibited interannual variability, and end of year dust concentrations were not necessarily related to the number of dust deposition events. Radiative forcing enhanced springtime melt by 21 to 51 days with the magnitude of advanced loss being linearly related to total dust concentration at the end of snow cover. To expand our understanding of dust on snow deposition patterns we utilize collections of dust concentration at the Colorado Dust on Snow (CODOS) study sites, established in 2009 along the western side of the CRB, to assess spatial variability in dust loading. In situ sampling of dust stratigraphy and concentration occurs twice each season, once over peak snow water equivalent (15 April), and again during melt (15 May). Dust loading occurs at all sites; dust concentrations are always higher in May, vary between sites, and the highest and lowest dust years were 2009 and 2012, respectively. In the absence of regular sampling and energy balance instrumentation these sites do not allow us to quantify the advanced melt due to dust. To facilitate this a new energy balance site, Grand Mesa Study plot (GMSP), was established for water year 2010 in west central Colorado, 150 km north of SBBSA. Back trajectories indicate similar Colorado Plateau dust sources at both SBBSA and GMSP, yet GMSP exhibits slightly lower dust

Dust generation in powders: Effect of particle size distribution

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Chakravarty Somik

2017-01-01

Full Text Available This study explores the relationship between the bulk and grain-scale properties of powders and dust generation. A vortex shaker dustiness tester was used to evaluate 8 calcium carbonate test powders with median particle sizes ranging from 2μm to 136μm. Respirable aerosols released from the powder samples were characterised by their particle number and mass concentrations. All the powder samples were found to release respirable fractions of dust particles which end up decreasing with time. The variation of powder dustiness as a function of the particle size distribution was analysed for the powders, which were classified into three groups based on the fraction of particles within the respirable range. The trends we observe might be due to the interplay of several mechanisms like de-agglomeration and attrition and their relative importance.

Exposure to respirable dust and manganese and prevalence of airways symptoms, among Swedish mild steel welders in the manufacturing industry.

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Hedmer, Maria; Karlsson, Jan-Eric; Andersson, Ulla; Jacobsson, Helene; Nielsen, Jörn; Tinnerberg, Håkan

2014-08-01

Welding fume consists of metal fumes, e.g., manganese (Mn) and gases, e.g., ozone. Particles in the respirable dust (RD) size range dominate. Exposure to welding fume could cause short- and long-term respiratory effects. The prevalence of work-related symptoms among mild steel welders was studied, and the occupational exposure to welding fumes was quantified by repeated measurements of RD, respirable Mn, and ozone. Also the variance components were studied. A questionnaire concerning airway symptoms and occupational history was answered by 79% of a cohort of 484 welders. A group of welders (N = 108) were selected and surveyed by personal exposure measurements of RD and ozone three times during 1 year. The welders had a high frequency of work-related symptoms, e.g., stuffy nose (33%), ocular symptoms (28%), and dry cough (24%). The geometric mean exposure to RD and respirable Mn was 1.3 mg/m(3) (min-max 0.1-38.3 mg/m(3)) and 0.08 mg/m(3) (min-max <0.01-2.13 mg/m(3)), respectively. More than 50% of the Mn concentrations exceeded the Swedish occupational exposure limit (OEL). Mainly, low concentrations of ozone were measured, but 2% of the samples exceeded the OEL. Of the total variance for RD, 30 and 33% can be attributed to within-worker variability and between-company variability, respectively. Welders had a high prevalence of work-related symptom from the airways and eyes. The welders' exposure to Mn was unacceptably high. To reduce the exposure further, control measures in the welding workshops are needed. Correct use of general mechanical ventilation and local exhaust ventilation can, for example, efficiently reduce the exposure.

The cost of respirable coal mine dust: an analysis based on new black lung claims

Energy Technology Data Exchange (ETDEWEB)

Page, S.J.; Organiscak, J.A.; Lichtman, K. [US Bureau of Mines, Pittsburgh, PA (United States). Dept. of the Interior

1997-12-01

The article provides summation of the monetary costs of new compensation claims associated with levels of unmitigated respirable coal mine dust and the resultant lung disease known as black lung and compares these compensation costs to the cost of dust control technology research by the US Bureau of Mines. It presents an analysis of these expenditures and projects these costs over the period from 1991 to 2010, based on projected future new claims which are assumed to be approved for federal and state benefit payment. Since current and future dust control research efforts cannot change past claim histories, a valid comparison of future research spending with other incurred costs must examine only the cost of future new claims. The bias of old claim costs was eliminated in this analysis by examining only claims since 1980. The results estimate that for an expected 339 new approved claims annually from 1991 to 2010, the Federal Trust Fund costs will be 985 million dollars. During this same period, state black lung compensation is estimated to be 18.2 billion dollars. The Bureau of Mines dust control research expenditures are estimated as 0.44% of the projected future black lung-related costs. 9 refs., 4 figs., 3 tabs.

A Computer-Controlled SEM-EDX Routine for Characterizing Respirable Coal Mine Dust

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Victoria Johann-Essex

2017-01-01

Full Text Available A recent resurgence in coal workers’ pneumoconiosis (or “black lung” and concerns over other related respiratory illnesses have highlighted the need to elucidate characteristics of airborne particulates in occupational environments. A better understanding of particle size, aspect ratio, or chemical composition may offer new insights regarding causal factors of such illnesses. Scanning electron microscopy analysis using energy dispersive X-ray (SEM-EDX can be used to estimate these particle characteristics. If conducted manually, such work can be very time intensive, limiting the number of particles that can be analyzed. Moreover, potential exists for user bias in interpretation of EDX spectra. A computer-controlled (CC routine, on the other hand, can allow similar analysis at a much faster rate, increasing total particle counts and reproducibility of results. This paper describes a CCSEM-EDX routine specifically developed for analysis of respirable dust samples from coal mines. The routine is verified based on reliability of results obtained on samples of known materials, and reproducibility of results obtained on a set of 10 dust samples collected in the field. The characteristics of the field samples are also discussed with respect to mine occupational environments.

Evaluation of Airborne MDF Dust Concentration in Furniture Factories

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Renilson Luiz Teixeira

2017-10-01

Full Text Available ABSTRACT High concentrations of airborne dust are observed during the cutting of medium density fiberboard (MDF boards. This dust, at first considered just uncomfortable for workers, may be harmful to their health. The objective of this work was to evaluate the concentration of airborne dust during the cutting of medium density fiberboard (MDF. The experiment was developed in the MDF cutting sector of three furniture factories located in the city of Lavras/MG. The results showed that the mean concentrations of total dust suspended in these three furniture factories were above the tolerance limit set by the American Conference of Governmental Industrial Hygienists (ACGIH, giving evidence of a serious problem in these companies related to this type of risk agent.

Dust Concentration and Emission in Protoplanetary Disks Vortices

Science.gov (United States)

Sierra, Anibal; Lizano, Susana; Barge, Pierre

2017-12-01

We study the dust concentration and emission in protoplanetary disks vortices. We extend the Lyra-Lin solution for the dust concentration of a single grain size to a power-law distribution of grain sizes n(a)\\propto {a}-p. Assuming dust conservation in the disk, we find an analytic dust surface density as a function of the grain radius. We calculate the increase of the dust-to-gas mass ratio ɛ and the slope p of the dust size distribution due to grain segregation within the vortex. We apply this model to a numerical simulation of a disk containing a persistent vortex. Due to the accumulation of large grains toward the vortex center, ɛ increases by a factor of 10 from the background disk value, and p decreases from 3.5 to 3.0. We find the disk emission at millimeter wavelengths corresponding to synthetic observations with ALMA and VLA. The simulated maps at 7 mm and 1 cm show a strong azimuthal asymmetry. This happens because, at these wavelengths, the disk becomes optically thin while the vortex remains optically thick. The large vortex opacity is mainly due to an increase in the dust-to-gas mass ratio. In addition, the change in the slope of the dust size distribution increases the opacity by a factor of two. We also show that the inclusion of the dust scattering opacity substantially changes the disks images.

The Development and Testing of a Prototype Mini-Baghouse to Control the Release of Respirable Crystalline Silica from Sand Movers

Science.gov (United States)

Alexander, Barbara M.; Esswein, Eric J.; Gressel, Michael G.; Kratzer, Jerry L.; Feng, H. Amy; King, Bradley; Miller, Arthur L.; Cauda, Emanuele

2016-01-01

Inhalation of respirable crystalline silica (RCS) is a significant risk to worker health during well completions operations (which include hydraulic fracturing) at conventional and unconventional oil and gas extraction sites. RCS is generated by pneumatic transfer of quartz-containing sand during hydraulic fracturing operations. National Institute for Occupational Safety and Health (NIOSH) researchers identified concentrations of RCS at hydraulic fracturing sites that exceed 10 times the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) and up to 50 times the NIOSH Recommended Exposure Limit (REL). NIOSH research identified at least seven point sources of dust release at contemporary oil and gas extraction sites where RCS aerosols were generated. NIOSH researchers recommend the use of engineering controls wherever they can be implemented to limit the RCS released. A control developed to address one of the largest sources of RCS aerosol generation is the NIOSH mini-baghouse assembly, mounted on the thief hatches on top of the sand mover. This manuscript details the results of a trial of the NIOSH mini-baghouse at a sand mine in Arkansas, November 18 – 21, 2013. During the trial, area air samples were collected at 12 locations on and around a sand mover with and without the mini-baghouse control installed. Analytical results for respirable dust and RCS indicate the use of the mini-baghouse effectively reduced both respirable dust and RCS downwind of the thief hatches. Reduction of airborne respirable dust ranged from 85% to 98%; reductions in airborne RCS ranged from 79% to 99%. A bulk sample of dust collected by the baghouse assembly showed the likely presence of freshly fractured quartz, a particularly hazardous form of RCS. Planned future design enhancements will increase the performance and durability of the mini-baghouse, including an improved bag clamp mechanism and upgraded filter fabric with a modified air-to-cloth ratio

Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

International Nuclear Information System (INIS)

Bengtsson, Goeran; Toerneman, Niklas; Yang Xiuhong

2010-01-01

Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added 13 C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass. - Hotspots of PAH biodegradation in a creosote contaminated soil do not coincide with hotspots of PAH concentration, microbial biomass and respiration.

Relationship between oxygen concentration, respiration and filtration rate in blue mussel Mytilus edulis

Science.gov (United States)

Tang, Baojun; Riisgård, Hans Ulrik

2018-03-01

The large water-pumping and particle-capturing gills of the filter-feeding blue mussel Mytilus edulis are oversized for respiratory purposes. Consequently, the oxygen uptake rate of the mussel has been suggested to be rather insensitive to decreasing oxygen concentrations in the ambient water, since the diffusion rate of oxygen from water flowing through the mussel determines oxygen uptake. We tested this hypothesis by measuring the oxygen uptake in mussels exposed to various oxygen concentrations. These concentrations were established via N2-bubbling of the water in a respiration chamber with mussels fed algal cells to stimulate fully opening of the valves. It was found that mussels exposed to oxygen concentrations decreasing from 9 to 2 mg O2/L resulted in a slow but significant reduction in the respiration rate, while the filtration rate remained high and constant. Thus, a decrease of oxygen concentration by 78% only resulted in a 25% decrease in respiration rate. However, at oxygen concentrations below 2 mg O2/L M. edulis responded by gradually closing its valves, resulting in a rapid decrease of filtration rate, concurrent with a rapid reduction of respiration rate. These observations indicated that M. edulis is no longer able to maintain its normal aerobic metabolism at oxygen concentration below 2 mg O2/L, and there seems to be an energy-saving mechanism in bivalve molluscs to strongly reduce their activity when exposed to low oxygen conditions.

Experimental studies of two-stage centrifugal dust concentrator

Science.gov (United States)

Vechkanova, M. V.; Fadin, Yu M.; Ovsyannikov, Yu G.

2018-03-01

The article presents data of experimental results of two-stage centrifugal dust concentrator, describes its design, and shows the development of a method of engineering calculation and laboratory investigations. For the experiments, the authors used quartz, ceramic dust and slag. Experimental dispersion analysis of dust particles was obtained by sedimentation method. To build a mathematical model of the process, dust collection was built using central composite rotatable design of the four factorial experiment. A sequence of experiments was conducted in accordance with the table of random numbers. Conclusion were made.

42 CFR 84.1130 - Respirators; description.

Science.gov (United States)

2010-10-01

...; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84...., dust clouds produced in mining, quarrying, and tunneling, and in dusts produced during industrial... respective vapors, or from the chemical reaction between their respective vapors and gases. (3) Air-purifying...

Interlaboratory comparison on 137Cs activity concentration in fume dust

International Nuclear Information System (INIS)

Tzika, Faidra; Hult, Mikael; Burda, Oleksiy; Arnold, Dirk; Sibbens, Goedele; Caro Marroyo, Belén; Gómez–Mancebo, Maria Belén; Peyrés, Virginia; Moser, Hannah; Ferreux, Laurent; Šolc, Jaroslav; Dryák, Pavel; Fazio, Aldo; Luca, Aurelian; Vodenik, Branko; Reis, Mario

2015-01-01

A comparison was conducted, between 11 European National Metrology Institutes and EC-JRC, on measurement of 137 Cs activity concentration in fume dust. As test material an activity standard produced from real contaminated fume dust was used. The standard material consisted of 13 cylindrical samples of compressed fume dust. The material contained 137 Cs and 60 Co of reference activity concentrations of (9.72±0.10) Bq/g and (0.450±0.018) Bq/g, respectively, for the reference date of 1 June 2013, determined using the comparison results. The organization and results of the intercomparison, as well as the process of obtaining reliable reference values are presented. - Highlights: • A European comparison was conducted on measurement of 137 Cs activity in fume dust. • Participants used high resolution gamma ray spectrometry. • Efficiency calibration included Monte Carlo, numerical and experimental methods. • Reference 137 Cs and 60 Co activity concentrations in the fume dust were determined. • A new traceable activity standard of fume dust matrix is available to end-users.

[Occupational exposure to silica dust by selected sectors of national economy in Poland based on electronic database].

Science.gov (United States)

Bujak-Pietrek, Stella; Mikołajczyk, Urszula; Szadkowska-Stańczyk, Irena; Stroszejn-Mrowca, Grazyna

2008-01-01

To evaluate occupational exposure to dusts, the Nofer Institute of Occupational Medicine in Łódź, in collaboration with the Chief Sanitary Inspectorate, has developed the national database to store the results of routine dust exposure measurements performed by occupational hygiene and environmental protection laboratories in Poland in the years 2001-2005. It was assumed that the collected information will be useful in analyzing workers' exposure to free crystalline silica (WKK)-containing dusts in Poland, identyfing exceeded hygiene standards and showing relevant trends, which illustrate the dynamics of exposure in the years under study. Inhalable and respirable dust measurement using personal dosimetry were done according to polish standard PN-91/Z-04030/05 and PN-91/Z-04030/06. In total, 148 638 measurement records, provided by sanitary inspection services from all over Poland, were entered into the database. The database enables the estimation of occupational exposure to dust by the sectors of national economy, according to the Polish Classification of Activity (PKD) and by kinds of dust. The highest exposure level of inhalable and respirable dusts was found in coal mining. Also in this sector, almost 60% of surveys demonstrated exceeded current hygiene standards. High concentrations of both dust fractions (inhalable and respirable) and a considerable percentage of measurements exceeding hygiene standards were found in the manufacture of transport equipment (except for cars), as well as in the chemical, mining (rock, sand, gravel, clay mines) and construction industries. The highest percentage of surveys (inhalable and respirable dust) showing exceeded hygiene standards were observed for coal dust with different content of crystalline silica, organic dust containing more than 10% of SiO2, and highly fibrosis dust containing more than 50% of SiO2.

Contributions of dust exposure and cigarette smoking to emphysema severity in coal miners in the United States

Energy Technology Data Exchange (ETDEWEB)

Kuempel, E.D.; Wheeler, M.W.; Smith, R.J.; Vallyathan, V.; Green, F.H.Y. [NIOSH, Cincinnati, OH (United States)

2009-08-15

Previous studies have shown associations between dust exposure or lung burden and emphysema in coal miners, although the separate contributions of various predictors have not been clearly demonstrated. The objective was to quantitatively evaluate the relationship between cumulative exposure to respirable coal mine dust, cigarette smoking, and other factors on emphysema severity. The study group included 722 autopsied coal miners and nonminers in the United States. Data on work history, smoking, race, and age at death were obtained from medical records and questionnaire completed by next-of-kin. Emphysema was classified and graded using a standardized schema. Job-specific mean concentrations of respirable coal mine dust were matched with work histories to estimate cumulative exposure. Relationships between various metrics of dust exposure (including cumulative exposure and lung dust burden) and emphysema severity were investigated in weighted least squares regression models. Emphysema severity was significantly elevated in coal miners compared with nonminers among ever- and never-smokers (P < 0.0001). Cumulative exposure to respirable coal mine dust or coal dust retained in the lungs were significant predictors of emphysema severity (P < 0.0001) after accounting for cigarette smoking, age at death, and race. The contributions of coal mine dust exposure and cigarette smoking were similar in predicting emphysema severity averaged over this cohort. Coal dust exposure, cigarette smoking, age, and race are significant and additive predictors of emphysema severity in this study.

Carbohydrate and protein contents of grain dusts in relation to dust morphology.

Science.gov (United States)

Dashek, W V; Olenchock, S A; Mayfield, J E; Wirtz, G H; Wolz, D E; Young, C A

1986-01-01

Grain dusts contain a variety of materials which are potentially hazardous to the health of workers in the grain industry. Because the characterization of grain dusts is incomplete, we are defining the botanical, chemical, and microbial contents of several grain dusts collected from grain elevators in the Duluth-Superior regions of the U.S. Here, we report certain of the carbohydrate and protein contents of dusts in relation to dust morphology. Examination of the gross morphologies of the dusts revealed that, except for corn, each dust contained either husk or pericarp (seed coat in the case of flax) fragments in addition to respirable particles. When viewed with the light microscope, the fragments appeared as elongated, pointed structures. The possibility that certain of the fragments within corn, settled, and spring wheat were derived from cell walls was suggested by the detection of pentoses following colorimetric assay of neutralized 2 N trifluoroacetic acid hydrolyzates of these dusts. The presence of pentoses together with the occurrence of proteins within water washings of grain dusts suggests that glycoproteins may be present within the dusts. With scanning electron microscopy, each dust was found to consist of a distinct assortment of particles in addition to respirable particles. Small husk fragments and "trichome-like" objects were common to all but corn dust. Images FIGURE 4. FIGURE 5. PMID:3709476

The effect of environmental parameters to dust concentration in air-conditioned space

Science.gov (United States)

Ismail, A. M. M.; Manssor, N. A. S.; Nalisa, A.; Yahaya, N.

2017-08-01

Malaysia has a wet and hot climate, therefore most of the spaces are air conditioned. The environment might affect dust concentration inside a space and affect the indoor air quality (IAQ). The main objective of this study is to study the dust concentration collected inside enclosed air-conditioned space. The measurement was done physically at four selected offices and two classrooms using a number of equipment to measure the dust concentration and environmental parameters which are temperature and relative air humidity. It was found that the highest dust concentration produced in office (temperature of 24.7°C, relative humidity of 66.5%) is 0.075 mg/m3, as compared to classroom, the highest dust concentration produced is 0.060 mg/m3 office (temperature of 25.9°C, relative humidity of 64.0%). However, both measurements show that value still within the safety level set by DOSH Malaysia (2005-2010) and ASHRAE 62.2 2016. The office contained higher dust concentration compared to classroom because of frequent movement transpires daily due to the functional of the offices.

[Analysis and prevention of dust pollution caused by 5 common prosthetic materials].

Science.gov (United States)

Yang, Xiang-Wen; Wei, Bin; Zhu, Cao-Yun; Qian, Liang; Li, Yi-Han

2017-10-01

To analyze and evaluate dust pollution in prosthodontic clinic and make proposal for reasonable protection. This study analyzed the particle size, element composition and dust concentration of 5 materials which were commonly used in dental restorations (veneering ceramics, cobalt-chromium alloy, photosensitive plastic, hard base resin, advanced artificial teeth) by using scanning electron microscopy (SEM), X-ray energy dispersive spectrometer（EDS） and dust concentration laser tester, in order to assess the effects of prosthodontic dust posed on medical staff health and put forward reasonable suggestions for prevention and control of dust pollution. The particle size of veneering ceramics, cobalt-chromium alloy, photosensitive plastic, hard base resin and advanced artificial teeth was (2.15±3.00), (33.78±24.33), (7.78±11.86), (31.16±44.35) and (28.45±39.21)μm, respectively. The time weighted average respirable dust concentration of veneering ceramics was 0.393 mg/m 2 which was beyond the scope of national security. Dust pollution is serious in prosthodontic clinic to which we should pay more attention and take appropriate prevention measures.

State of the art in monitoring respirable mine aerosols

Energy Technology Data Exchange (ETDEWEB)

Volkwein, J.C.; Mischler, S.E.; Thimons, E.D.; Timko, R.J.; Kissell, F.N.

2005-07-01

The Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH) has been developing several new tools to help miners monitor respirable coal dust, silica, and diesel particulate matter. This paper discusses three main topics. First, the latest results of the person wearable dust monitor (PDM), developed by Rupprecht and Patashnick under CDC contract. The PDM was tested side by side with conventional samplers at a number of US coal mines and results indicated that the PDM was comparable to conventional samplers. Second, improvements to the Dust Dosimeter monitoring technique that includes a new pump with built in pressure transducer and algorithm to convert differential pressure to dust concentration have shown good precision. Third, advances in the use of the detector tube technique to monitor tailpipe diesel emissions and ambient diesel particulate matter show that strong correlations exist between differential pressure measurement and elemental carbon in the samplers. 3 figs.

Long-range Transported African Dust in the Caribbean Region: Dust Concentrations and Water-soluble Ions

Science.gov (United States)

Santos-Figueroa, G.; Avilés-Piñeiro, G. M.; Mayol-Bracero, O. L.

2017-12-01

Long-range transported African dust (LRTAD) particles reach the Caribbean region every year during the summer months causing an increase in PM10 concentrations and by consequence degradation of air quality. During African dust (AD) incursions at the Caribbean region, PM10 concentration could exceeds the exposure limit of 50 µg/m³ 24-hour mean established by the World Health Organization (WHO). To have a better understanding of the impacts of AD particles to climate and public health at the Caribbean region it is necessary to study and determine the spatial and temporal distribution of dust particles. In order to address this, aerosols samples were collected during and absence of AD incursions during the summer of 2017 using a Hi-Volume (Hi-Vol) sampler for total suspended particles (TSP) at two sampling stations in Puerto Rico. The first station is a marine site located at Cabezas de San Juan (CSJ) Nature Reserve in Fajardo, and the second station is an urban site located at the Facundo Bueso (FB) building at the University of Puerto Rico-Rio Piedras. Aerosol samples were collected using Whatman 41 grade filters from which we determined the concentration of dust particles and the water-soluble ions (e.g., Na+, NH4+, Ca+2, Cl-, SO4-2) in the presence and absence of LRTAD particles. Saharan Air Layer (SAL) imagery, the results from the air mass backward trajectories calculated with the NOAA Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), and the spectral coefficients from measurements at CSJ were used to monitor and confirm the presence of air masses coming from North Africa. Average dust concentrations using the Stacked-Filter Units (SFUs) at CSJ are around 4 μg/m3. LRTAD concentrations and ionic speciation results using the Hi-Vol for the marine and urban sites will be presented at the conference.

Lunar Dust Separation for Toxicology Studies

Science.gov (United States)

Cooper, Bonnie L.; McKay, D. S.; Riofrio, L. M.; Taylor, L. A.; Gonzalex, C. P.

2010-01-01

During the Apollo missions, crewmembers were briefly exposed to dust in the lunar module, brought in after extravehicular activity. When the lunar ascent module returned to micro-gravity, the dust that had settled on the floor now floated into the air, causing eye discomfort and occasional respiratory symptoms. Because our goal is to set an exposure standard for 6 months of episodic exposure to lunar dust for crew on the lunar surface, these brief exposures of a few days are not conclusive. Based on experience with industrial minerals such as sandblasting quartz, an exposure of several months may cause serious damage, while a short exposure may cause none. The detailed characteristics of sub-micrometer lunar dust are only poorly known, and this is the size range of particles that are of greatest concern. We have developed a method for extracting respirable dust (<2.5 micron) from Apollo lunar soils. This method meets stringent requirements that the soil must be kept dry, exposed only to pure nitrogen, and must conserve and recover the maximum amount of both respirable dust and coarser soil. In addition, we have developed a method for grinding coarser lunar soil to produce sufficient respirable soil for animal toxicity testing while preserving the freshly exposed grain surfaces in a pristine state.

Characteristic of ambient airborne and respirable particulate around a non formal industrial area

International Nuclear Information System (INIS)

Muhayatun Santoso; Diah Dwiana Lestiani; Mariana Marselina; Rita Mukhtar

2016-01-01

Characterization of airborne particulate matter and respirable particulate in Parung Panjang district especially on surrounding non formal used batteries industrial area has been carried out to follow up the previous results with respect to high concentrations of lead detected in Serpong area. Sampling of airborne particulate matter in Parung Panjang was conducted using Gent stacked filter unit sampler, while the respirable particulate matter samples collected using personal dust sampler in Parung Panjang as a non formal Industrial area and Sukarasa village as a control, during 2011-2012. The concentration of masses were determined gravimetrically, while for elemental concentrations by X-Ray based methods. The average of mass concentration of air ambient PM 2.5 and PM 10 in Parung Panjang were 27.3 ± 13.7 and 77.5 ± 17.1 μg.m -3 , respectively. While the average concentration of respirable particulate in non formal industrial and control areas were 260 ± 233 and 82 ± 38 μg.m -3 , respectively. The percentage of average Pb concentration in PM 2.5 and PM 2.5-10 were contribute up to 45 and 10 % of the mass concentration, respectively. The maximum percentage concentration of Pb in respirable particulate in industrial and control area were 12.11 and 0.27 %, respectively. These results showed that the Pb concentrations in respirable particulate in industrial area were significantly tens times higher than in the control area. The high concentration of Pb in Parung Panjang was the main key element came from the used lead battery industry and one of pollutant source that contributed to the Pb pollution in Serpong area. (author)

Grain elevator workers show work-related pulmonary function changes and dose-effect relationships with dust exposure.

Science.gov (United States)

Corey, P; Hutcheon, M; Broder, I; Mintz, S

1982-01-01

The purpose of this study was to determine whether grain handlers underwent work-related changes in their pulmonary function and, if so, to examine the dose-effect relationships with dust exposure. The pulmonary function of grain handlers was measured at the beginning and end of work shifts over a period of one week, during which their exposure to dust was measured daily. The results showed changes indicative of a within-day obstructive change, in addition to a small restrictive defect occurring over the course of a week. Civic outside labourers who were examined as a control group showed a similar within-week obstructive change without any associated restriction of lung volume. The data on the grain handlers were also used to examine the dose-effect relationships of dust exposure, both on baseline pulmonary function and on within-day changes in these measurements. The baseline flow rates of workers who did not wear a mask were found to vary inversely with their average exposure to respirable dust. In addition, the flow rates underwent a within-day decrease that varied directly with their corresponding exposure to respirable dust and was unrelated to mask wearing. The median of the slopes for this relationship indicated that 50% of the subjects had a decrease of at least 923 ml/s in the value of their Vmax50%VC for each 1 mg/m3 increase in the concentration of respirable dust. Non-respirable dust did not have a measurable effect either on the baseline or the within-day changes in pulmonary function. The acute changes were unaffected by age, duration of employment, or extent of smoking. PMID:7138793

Evaluation of Simultaneous Exposure to Flour Dust and Airborne Fungal Spores in Milling Plant

Directory of Open Access Journals (Sweden)

Alireza Dehdashti

2016-01-01

Full Text Available Background and Objectives: Wheat flour as an organic allergen particle has an extensive respiratory exposure in milling industry and related industries. Simultaneous exposure to flour dust and fungal spores causes infectious disease, cancers, and impaired pulmonary function tests. This research was carried out with the aim of assessing the concentration of respirable flour particles, determining the type, and concentration of fungal spores in breathing air of workers in milling industries. Methods: In this descriptive cross-sectional study, 42 area samples were collected on filter and analyzed gravimetrically. Using a specific sampling pump, sampling of bioaerosols and sabro dextrose agar medium of fungal spores, was performed. Microscopic analysis was applied to detect and quantify microorganisms as colony per cubic meter. Results: The mean and standard deviation of total respirable particles in the breathing air of workers was 6/57±1/69mg/m3, which exceeded occupational exposure limit. The concentration of fungal spores in workers’ breathing air ranged from 42 to 310 colony per cubic meter. The percentage of respirable to total dust particles produced in sieve vibration, bagging, and milling sections, were determined 67.83%, 32%, and 62.2%, respectively. Conclusion: The results of this study revealed that the concentration of respirable particles in wheat milling process exceeded the recommended level and the concentration of fungal spores was at the average level of occupational exposure according to ACGIH recommendation. Therefore, engineering controls are required in flour milling process to reduce the exposure of workers.

Impact of cement dust on the mineral and energy concentration of Psidium guayava

Energy Technology Data Exchange (ETDEWEB)

Lai, B.; Ambasht, R.S.

1982-12-01

The impact of cement dust deposition on mineral and energy concentration of leaves of guava Psidium guayava growing in the vicinity of Churk Dement Factory situated at Churk, District-Mirzapur (India) was studied. Concentrations of calcium (Ca), potassium (K), sodium (Na) and phosphorus (P) were increased while energy content (cal g/sup -1/ dry weight) was reduced (12.3%) more in cement-dust-covered leaves than in dust-free leaves of Psidium guayava. Statistically it was found that the difference in the concentration of Ca, K, and P industry and dust-free leaves was highly correlated and significant with the amount of cement dust deposited (gm/sup -2/ leaf surface) on the leaf surface of P. guayava while the difference in the concentration of Na--although positively correlated--is not significant. Maximum values of concentrations of Ca, K, Na, P and energy were 5.20%, 0.48%, 0.025%, 0.15% and 4936.7 cal g/sup -1/ dry weight in dust-covered leaves and 3.50%, 0.30%, 0.018%, 0.12% and 5301.4 cal g/sup -1/ dry weight in dust-free leaves, respectively.

Effect of wind speed and relative humidity on atmospheric dust concentrations in semi-arid climates.

Science.gov (United States)

Csavina, Janae; Field, Jason; Félix, Omar; Corral-Avitia, Alba Y; Sáez, A Eduardo; Betterton, Eric A

2014-07-15

Atmospheric particulate have deleterious impacts on human health. Predicting dust and aerosol emission and transport would be helpful to reduce harmful impacts but, despite numerous studies, prediction of dust events and contaminant transport in dust remains challenging. In this work, we show that relative humidity and wind speed are both determinants in atmospheric dust concentration. Observations of atmospheric dust concentrations in Green Valley, AZ, USA, and Juárez, Chihuahua, México, show that PM10 concentrations are not directly correlated with wind speed or relative humidity separately. However, selecting the data for high wind speeds (>4m/s at 10 m elevation), a definite trend is observed between dust concentration and relative humidity: dust concentration increases with relative humidity, reaching a maximum around 25% and it subsequently decreases with relative humidity. Models for dust storm forecasting may be improved by utilizing atmospheric humidity and wind speed as main drivers for dust generation and transport. Copyright © 2014 Elsevier B.V. All rights reserved.

[Comparative studies of personal and steady-state sampling for determining dust exposure in different job groups].

Science.gov (United States)

Cherneva, P; Lukanova, R

1994-01-01

The variability of the dust concentration in time and space, as well as the change of worker's place during the working process, define the necessity of introducing personal sampling in the hygiene control practice. However, the laboratory equipment with personal devices is still not sufficient. The aim of this work is to assess the dust exposure of the basic professional groups from the ore- and coal production in Bulgaria by personal sampling in comparative studies of the static ambient sampling used up to now. 63 full-shift investigations of the dust factor were performed on professional groups of miners of the polymetal and coal pits by static ambient devices-[Hygitest production] and personal [from firms "Casella", "Strolein" and "Gilian"] devices, after standardized methods. The results are data processed-by means of logarithmic normal distribution of the relation of the respirable dust concentrations, determined personally and by static ambient sampling. The limits of variation of this correlation are from 0.5 to 4.1 at average geometric value -0.95 and standard geometric deviation-1.8 i.e. both types of sampling are intersubstitutional for the examined groups and sites, as in the underground ores the professional risk of respirable dust is underestimated up to 4 times at static ambient sampling.

Elemental concentrations in deposited dust on leaves along an urbanization gradient.

Science.gov (United States)

Simon, Edina; Baranyai, Edina; Braun, Mihály; Cserháti, Csaba; Fábián, István; Tóthmérész, Béla

2014-08-15

Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP-OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree. Copyright © 2014 Elsevier B.V. All rights reserved.

Elemental concentrations in deposited dust on leaves along an urbanization gradient

Energy Technology Data Exchange (ETDEWEB)

Simon, Edina, E-mail: edina.simon@gmail.com [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Baranyai, Edina [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Agilent Atomic Spectroscopy Partner Laboratory, University of Debrecen, Egyetem tér 1, H-4032 Debrecen (Hungary); Braun, Mihály [Institute of Nuclear Research of the Hungarian Academy of Sciences, Herteleni Laboratory of Environmental Studies, 4026 Debrecen, Bem tér 18/C (Hungary); Cserháti, Csaba [Department of Solid State Physics, University of Debrecen, H-4010 Debrecen, P.O. Box 2 (Hungary); Fábián, István [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Tóthmérész, Béla [HAS-UD Biodiversity and Ecosystem Services Research Group, H-4010 Debrecen, P.O. Box 71 (Hungary)

2014-08-15

Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP–OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree. - Highlights: • Dust is used as indicators of the accumulation of inorganic pollutants. • Scanning EM was used to explore the morphological structure of leaves. • Amount of dust deposited of leaves correlated with trichomes' density. • A. negundo, C. occidentalis and Q. robur are suitable to indicate air contaminants. • A. negundo and C. occidentalis are suitable to decrease the amount of dust in air.

Elemental concentrations in deposited dust on leaves along an urbanization gradient

International Nuclear Information System (INIS)

Simon, Edina; Baranyai, Edina; Braun, Mihály; Cserháti, Csaba; Fábián, István; Tóthmérész, Béla

2014-01-01

Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP–OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree. - Highlights: • Dust is used as indicators of the accumulation of inorganic pollutants. • Scanning EM was used to explore the morphological structure of leaves. • Amount of dust deposited of leaves correlated with trichomes' density. • A. negundo, C. occidentalis and Q. robur are suitable to indicate air contaminants. • A. negundo and C. occidentalis are suitable to decrease the amount of dust in air

Temperature response of soil respiration is dependent on concentration of readily decomposable C

Science.gov (United States)

Larionova, A. A.; Yevdokimov, I. V.; Bykhovets, S. S.

2007-12-01

Temperature acclimation of soil organic matter (SOM) decomposition is one of the major uncertainties in predicting soil CO2 efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006) based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax) and half-saturation constant (Ks) cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents) and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

Soil and Root Respiration Under Elevated CO2 Concentrations During Seedling Growth of Pinus sylvestris var. sylvestriformis

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The objectives of this study were to investigate the effect of higher CO2 concentrations (500 and 700 μmol mol-1) in atmosphere on total soil respiration and the contribution of root respiration to total soil respiration during seedling growth of Pinus sylvestris var. sylvestriformis. During the four growing seasons (May-October) from 1999 to 2003, the seedlings were exposed to elevated concentrations of CO2 in open-top chambers. The total soil respiration and contribution of root respiration were measured using an LI-6400-09 soil CO2 flux chamber on June 15 and October 8, 2003. To separate root respiration from total soil respiration, three PVC cylinders were inserted approximately 30 cm deep into the soil in each chamber. There were marked diurnal changes in air and soil temperatures on June 15. Both the total soil respiration and the soil respiration without roots showed a strong diurnal pattern, increasing from before sunrise to about 14:00in the afternoon and then decreasing before the next sunrise. No increase in the mean total soil respiration and mean soil respiration with roots severed was observed under the elevated CO2 treatments on June 15, 2003, as compared to the open field and control chamber with ambient CO2. However, on October 8, 2003, the total soil respiration and soil respiration with roots severed in the open field were lower than those in the control and elevated CO2 chambers. The mean contribution of root respiration measured on June 15, 2003, ranged from 8.3% to 30.5% and on October 8, 2003,from 20.6% to 48.6%.

Saharan Dust Particle Size And Concentration Distribution In Central Ghana

Science.gov (United States)

Sunnu, A. K.

2010-12-01

A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for

Method and equipment to determine fine dust concentrations

International Nuclear Information System (INIS)

Breuer, H.; Gebhardt, J.; Robock, K.

1979-01-01

The measured values for the fine dust concentration are obtained by optical means which where possible agree with the probable deposited quantity of fine dust in the pulmonary alveoli. This is done by receiving the strong radiation produced in dependence of the particle size at an angle of 70 0 to the angle of incidence of the primary beam. The wavelength of the primary radiation is in the region of 1000 to 2000 nm. (RW) [de

Heavy metal concentration of settled surface dust in residential building

International Nuclear Information System (INIS)

Nor Aimi abdul Wahab; Fairus Muhamad Darus; Norain Isa; Siti Mariam Sumari; Nur Fatihah Muhamad Hanafi

2012-01-01

The concentrations of heavy metals (Cu, Ni, Pb and Zn) in settled surface dust were collected from nine residential buildings in different areas in Seberang Prai Tengah District, Pulau Pinang. The samples of settled surface dust were collected in 1 m 2 area by using a polyethylene brush and placed in the dust pan by sweeping the living room floor most accessible to the occupants. Heavy metals concentrations were determined by using inductively coupled plasma optical emission spectrometer (ICP-OES) after digestion with nitric acid and sulphuric acid. The results show that the range of heavy metals observed in residential buildings at Seberang Prai Tengah were in the range of 2.20-14.00 mg/ kg, 1.50-32.70 mg/ kg, 1.50-76.80 mg/ kg and 14.60-54.40 mg/ kg for Cu, Ni, Pb and Zn respectively. The heavy metal concentration in the investigated areas followed the order: Pb > Zn > Ni > Cu. Statistical analysis indicates significant correlation between all the possible pairs of heavy metal. The results suggest a likely common source for the heavy metal contamination, which could be traced most probably to vehicular emissions, street dust and other related activities. (author)

Temperature response of soil respiration is dependent on concentration of readily decomposable C

Directory of Open Access Journals (Sweden)

A. A. Larionova

2007-12-01

Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO₂ efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (V_max and half-saturation constant (K_s cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than K_s. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate V_max leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

Exposure to dust mixtures containing free crystalline silica and mineral fibers

International Nuclear Information System (INIS)

Wozniak, H.; Wiecek, E.; Bielichowska-Cybula, G.

1996-01-01

Exposure to dust mixture containing at the same time respirable mineral fibres and free crystalline silica may occur in Poland in mines and in the Lower Silesia plants processing mineral raw materials as well as in all plants which use asbestos products and MMMF. Workposts where thermal insulation is exchange with possible phase transformations during operations under conditions of high temperature, expose particularly complex problems. In the work environment of this kind, dust concentration of free crystalline silica becomes important but not sufficient criterion for evaluating working conditions and it may be misleading. A range of studies indispensable for the proper evaluation of exposure to dust, covering together with measurement of dust and SiO 2 concentrations, determination of the mineral composition of dust, was developed. It was also found that the acceptable level of risk for neoplastic disease, namely 10(-3) can be attained in the work environment only if the concentration ranges from 0.05 to 0.1 f/cm 3 , that is equal to 20% of MAC value which is now binding in Poland. Cancer risk (lung cancer and mesothelioma jointly) during a 20-year exposure to concentrations equal to present MAC values should be estimated as about 10(-2) what indicates that risk is too high and it is necessary to diminish MAC values for asbestos dust. (author). 17 refs, 3 tabs

An analysis of employee exposure to organic dust at large-scale composting facilities

Science.gov (United States)

Sykes, P.; Allen, J. A.; Wildsmith, J. D.; Jones, K. P.

2009-02-01

The occupational health implications from exposure to dust, endotoxin and 1-3 β Glucan at commercial composting sites are uncertain. This study aims to establish employee exposure levels to inhalable and respirable dust, endotoxin and 1-3 β Glucan during various operational practices in the composting process. Personal samples were collected and the inhalable and respirable dust fractions were determined by gravimetric analysis. Endotoxin concentrations were determined using a Limulus Amebocyte Lysate assay (LAL). 1-3 β Glucan levels were estimated using a specific blocking agent to establish the contribution that these compounds gave to the original endotoxin assay. Employees' exposure to dust was found to be generally lower than the levels stipulated in the Control of Substances Hazardous to Health Regulations (COSHH) 2002 (as amended), (median inhalable fraction 1.08 mg/m3, min 0.25 mg/m3 max 10.80 mg/m3, median respirable fraction 0.05 mg/m3, min 0.02 mg/m3, max 1.49 mg/m3). Determination of the biological component of the dust showed that employees' exposures to endotoxin were elevated (median 31.5 EU/m3, min 2.00 EU/m3, max 1741.78 EU/m3), particularly when waste was agitated (median 175.0 EU/m3, min 2.03 EU/m3, max 1741.78 EU/m3). Eight out of 32 (25%) of the personal exposure data for endotoxin exceeded the 200 EU/m3 temporary legal limit adopted in the Netherlands and thirteen out of 32 (40.6%) exceeded the suggested 50 EU/m3 guidance level suggested to protect workers from respiratory health effects. A significant correlation was observed between employee inhalable dust exposure and personal endotoxin concentration (r = 0.728, phealth risks associated with endotoxin exposure at composting sites. Employee exposure levels and dose-response disease mechanisms are not well understood at this present time. Consequently, in light of this uncertainty, it is recommended that a precautionary approach be adopted in managing the potential health risks associated

Respirable coal dust exposure and respiratory symptoms in South-African coal miners: A comparison of current and ex-miners

Energy Technology Data Exchange (ETDEWEB)

Naidoo, R.N.; Robins, T.G.; Seixas, N.; Lalloo, U.G.; Becklake, M. [University of KwaZuluNatal, Congella (South Africa). Nelson R Mandela School of Medicine

2006-06-15

Dose-response associations between respirable dust exposure and respiratory symptoms and between symptoms and spirometry outcomes among currently employed and formerly employed South-African coal miners were investigated. Work histories, interviews, and spirometry and cumulative exposure were assessed among 684 current and 212 ex-miners. Results: Lower prevalences of symptoms were found among employed compared with ex-miners. Associations with increasing exposure for symptoms of phlegm and past history of tuberculosis were observed, whereas other symptom prevalences were higher in the higher exposure categories. Symptomatic ex-miners exhibited lower lung-function compared to the nonsymptomatic. Compared with published data, symptoms rates were low in current miners but high in ex-miners. Although explanations could include the low prevalence of smoking and/or reporting/selection bias, a 'Survivor' and/or a 'hire' effect is more likely, resulting in an underestimation of the dust-related effect.

Soil CO2 concentration does not affect growth or root respiration in bean or citrus

NARCIS (Netherlands)

Bouma, T.J.; Nielsen, K.F.; Eissenstat, D.M.; Lynch, J.P.

1997-01-01

Contrasting effects of soil CO2 concentration on root respiration rates during short-term CO2 exposure, and on plant growth during long-term CO2 exposure, have been reported, Here we examine the effects of both short-and long-term exposure to soil CO2 on the root respiration of intact plants and on

Pulmonary epithelial response in the rat lung to instilled Montserrat respirable dusts and their major mineral components.

Science.gov (United States)

Housley, D G; Bérubé, K A; Jones, T P; Anderson, S; Pooley, F D; Richards, R J

2002-07-01

The Soufriere Hills, a stratovolcano on Montserrat, started erupting in July 1995, producing volcanic ash, both from dome collapse pyroclastic flows and phreatic explosions. The eruptions/ash resuspension result in high concentrations of suspended particulate matter in the atmosphere, which includes cristobalite, a mineral implicated in respiratory disorders. To conduct toxicological studies on characterised samples of ash, together with major components of the dust mixture (anorthite, cristobalite), and a bioreactive mineral control (DQ12 quartz). Rats were challenged with a single mass (1 mg) dose of particles via intratracheal instillation and groups sacrificed at one, three, and nine weeks. Acute bioreactivity of the particles was assessed by increases in lung permeability and inflammation, changes in epithelial cell markers, and increase in the size of bronchothoracic lymph nodes. Data indicated that respirable ash derived from pyroclastic flows (20.1% cristobalite) or phreatic explosion (8.6% cristobalite) had minimal bioreactivity in the lung. Anorthite showed low bioreactivity, in contrast to pure cristobalite, which showed progressive increases in lung damage. Results suggests that either the percentage mass of cristobalite particles present in Montserrat ash was not sufficient as a catalyst in the lung environment, or its surface reactivity was masked by the non-reactive volcanic glass components during the process of ash formation.

Elemental Concentration of Inhalable and Respirable Particulate ...

African Journals Online (AJOL)

20537 and respirable foam for I.O.M sampler. The elemental composition (Co, Ni, Zn, Cu, Fe, Pb, Cr, Mn and Cd) were analyzed by using Atomic Absorption Spectrophotometric (AAS). The data generated were subjected to descriptive analysis. In inhalable fraction,the enrichment factor ranged from 1-73.3 while in respirable ...

Lead Concentration in Primary School Soil-Dust in Nigeria, Africa

Directory of Open Access Journals (Sweden)

Ekwumemgbo P. A.

2013-04-01

Full Text Available Lead in soil has been recognized as a public health problem, particularly among children. In recent years, attention has been directed to cumulative adverse effects of lead at low levels of intake. Leadcontaminated soil and dust have been identified as important contributors to blood lead levels. This work examines the total concentration of lead in primary school soil-dust in Nigeria. Soil-dusts were collected randomly from six geopolitical areas of Nigeria, digested and analysed for total lead concentration by Atomic Absorption Spectrophotometry. The mean lead concentration in the dry season for the North East (NE, North West (NW, North Central (NC, South South (SS, South East (SE, South West (SW were 131.60 ± 70.98 mg/kg, 108.04 ± 47.33 mg/kg, 72.94 ± 55.45 mg/kg, 66.14 ± 43.9 mg/kg, 45.98 ± 34.60 mg/kg and 67.98 ± 34.89 mg/kg respectively. In the raining season the mean lead concentration were 130.78 ± 70.80 mg/kg, 106.24 ± 47.02 mg/kg, 70.96 ± 55.52 mg/kg, 64.12 ± 48.00 mg/kg, 44.58 ± 28.90 mg/kg, and 66.26 ± 41.87 mg/kg respectively. This analysis is necessary to provide scientific data base for the loading of lead in classroom soil-dust in each zone. The authors recommend measurement and surveillance of lead blood level of the primary school children and a clean-up of both classrooms and the school environment.

Response of needle dark respiration of Pinus koraiensis and Pinus sylvestriformis to elevated CO2 concentrations for four growing seasons' exposure

Institute of Scientific and Technical Information of China (English)

ZHOU YuMei; HAN ShiJie; ZHANG HaiSen; XIN LiHua; ZHENG JunQiang

2007-01-01

The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous species-Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. Koraiensis and P. Sylvestriformis were exposed to 700,500μmol·mol-1 CO2 and ambient CO2(approx.350 μmol·mol-1)for four growing seasons. Needle dark respiration was measurd during the second, third and fourth growing seasons' exposure to elevated CO2.The results showed that needle dark respiration rate increased for P. Koraiensis and P. Sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. Koraiensis was stimulated and that of P. Sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. Koraiensis and P. Sylvestriformis during the fourth growing season. There was consistent trend between the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. Sylvestriformis during the third growing season by changing measurement CO2 concentrations. However, the short-term effect was different from the long-term effect for P. Koraiensis. Response of dark respiration of P. Koraiensis and P. Sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.

Worker exposure to silica dust in South African non-mining industries in Gauteng: An exploratory study

CSIR Research Space (South Africa)

Khoza, NN

2012-06-01

Full Text Available %, and sandblasting 2.4%. The overall maximum and minimum exposures were 5.772 and 0.009 mg/m?, respectively. Conclusion: Workers are potentially at high risk of contracting silicosis and other diseases associated with respirable silica dust. Dust control... and monitoring were inadequate in the industries visited. It is recommended that an in-depth study be conducted and that airborne dust-control programmes be implemented. Key words: non-mining industries, silica dust, respirable crystalline silica dust...

Cause-specific mortality in British coal workers and exposure to respirable dust and quartz

Energy Technology Data Exchange (ETDEWEB)

Miller, B.G.; MacCalman, L. [Institute of Occupational Medicine, Edinburgh (United Kingdom)

2010-04-15

In the 1950s the Pneumoconiosis Field Research (PFR) programme was set up to study the health of British coal workers. Studies included regular health surveys, an intensive characterisation of workers' individual exposures, and entry to a cohort followed up to the present for cause-specific mortality. This study reports on analyses of cause-specific mortality in a cohort of almost 18 000 men from 10 British collieries. External analyses used standardised mortality ratios (SMRs), comparing observed mortality with reference rates from the regions in which the collieries were situated. Causes investigated include lung and stomach cancers, chronic obstructive pulmonary disease and cardiovascular endpoints. Internal analyses used Cox regression models with time-dependent exposures adjusting for the confounding effects of age, smoking, cohort entry date and regional differences in population mortality rates. Several causes showed evidence of a healthy worker effect early in the follow-up, with a deficit in the SMR diminishing over time. For most of the causes there was a significant excess in the latter part of follow-up. Internal analyses found evidence of an association between increased risks of lung cancer and increased quartz exposure, particularly at a lag of 15 years. Risks of mortality from non-malignant respiratory disease showed increases with increased exposure to respirable dust. This paper adds to the evidence on the long-term effects of exposure to coalmine dust on mortality from respiratory diseases.

Cause-specific mortality in British coal workers and exposure to respirable dust and quartz

Energy Technology Data Exchange (ETDEWEB)

Brian G Miller; Laura MacCalman [Institute of Occupational Medicine, Edinburgh (United Kingdom)

2010-04-15

In the 1950s the Pneumoconiosis Field Research (PFR) programme was set up to study the health of British coal workers. Studies included regular health surveys, an intensive characterisation of workers' individual exposures, and entry to a cohort followed up to the present for cause-specific mortality. This study reports on analyses of cause-specific mortality in a cohort of almost 18?000 men from 10 British collieries. External analyses used standardised mortality ratios (SMRs), comparing observed mortality with reference rates from the regions in which the collieries were situated. Causes investigated include lung and stomach cancers, chronic obstructive pulmonary disease and cardiovascular endpoints. Internal analyses used Cox regression models with time-dependent exposures adjusting for the confounding effects of age, smoking, cohort entry date and regional differences in population mortality rates. Several causes showed evidence of a healthy worker effect early in the follow-up, with a deficit in the SMR diminishing over time. For most of the causes there was a significant excess in the latter part of follow-up. Internal analyses found evidence of an association between increased risks of lung cancer and increased quartz exposure, particularly at a lag of 15 years. Risks of mortality from non-malignant respiratory disease showed increases with increased exposure to respirable dust. This paper adds to the evidence on the long-term effects of exposure to coalmine dust on mortality from respiratory diseases.

Effect of ecological restoration programs on dust concentrations in the North China Plain: a case study

Science.gov (United States)

Long, Xin; Tie, Xuexi; Li, Guohui; Cao, Junji; Feng, Tian; Zhao, Shuyu; Xing, Li; An, Zhisheng

2018-05-01

In recent decades, the Chinese government has made a great effort in initiating large-scale ecological restoration programs (ERPs) to reduce the dust concentrations in China, especially for dust storm episodes. Using the Moderate Resolution Imaging Spectroradiometer (MODIS) land cover product, the ERP-induced land cover changes are quantitatively evaluated in this study. Two obvious vegetation protective barriers arise throughout China from the southwest to the northeast, which are well known as the Green Great Wall (GGW). Both the grass GGW and forest GGW are located between the dust source region (DSR) and the densely populated North China Plain (NCP). To assess the effect of ERPs on dust concentrations, a regional transport/dust model (WRF-DUST, Weather Research and Forecast model with dust) is applied to investigate the evolution of dust plumes during a strong dust storm episode from 2 to 8 March 2016. The WRF-DUST model generally performs reasonably well in reproducing the temporal variations and spatial distributions of near-surface [PMC] (mass concentration of particulate matter with aerodynamic diameter between 2.5 and 10 µm) during the dust storm event. Sensitivity experiments have indicated that the ERP-induced GGWs help to reduce the dust concentration in the NCP, especially in BTH (Beijing, Tianjin, and Hebei). When the dust storm is transported from the upwind DSR to the downwind NCP, the [PMC] reduction ranges from -5 to -15 % in the NCP, with a maximum reduction of -12.4 % (-19.2 µg m-3) in BTH and -7.6 % (-10.1 µg m-3) in the NCP. We find the dust plumes move up to the upper atmosphere and are transported from the upwind DSR to the downwind NCP, accompanied by dust decrease. During the episode, the forest GGW is nonsignificant in dust concentration control because it is of benefit for dry deposition and not for emission. Conversely, the grass GGW is beneficial in controlling dust erosion and is the dominant reason for [PMC] decrease in the NCP

Effect of ecological restoration programs on dust concentrations in the North China Plain: a case study

Directory of Open Access Journals (Sweden)

X. Long

2018-05-01

Full Text Available In recent decades, the Chinese government has made a great effort in initiating large-scale ecological restoration programs (ERPs to reduce the dust concentrations in China, especially for dust storm episodes. Using the Moderate Resolution Imaging Spectroradiometer (MODIS land cover product, the ERP-induced land cover changes are quantitatively evaluated in this study. Two obvious vegetation protective barriers arise throughout China from the southwest to the northeast, which are well known as the Green Great Wall (GGW. Both the grass GGW and forest GGW are located between the dust source region (DSR and the densely populated North China Plain (NCP. To assess the effect of ERPs on dust concentrations, a regional transport/dust model (WRF-DUST, Weather Research and Forecast model with dust is applied to investigate the evolution of dust plumes during a strong dust storm episode from 2 to 8 March 2016. The WRF-DUST model generally performs reasonably well in reproducing the temporal variations and spatial distributions of near-surface [PMC] (mass concentration of particulate matter with aerodynamic diameter between 2.5 and 10 µm during the dust storm event. Sensitivity experiments have indicated that the ERP-induced GGWs help to reduce the dust concentration in the NCP, especially in BTH (Beijing, Tianjin, and Hebei. When the dust storm is transported from the upwind DSR to the downwind NCP, the [PMC] reduction ranges from −5 to −15 % in the NCP, with a maximum reduction of −12.4 % (−19.2 µg m−3 in BTH and −7.6 % (−10.1 µg m−3 in the NCP. We find the dust plumes move up to the upper atmosphere and are transported from the upwind DSR to the downwind NCP, accompanied by dust decrease. During the episode, the forest GGW is nonsignificant in dust concentration control because it is of benefit for dry deposition and not for emission. Conversely, the grass GGW is beneficial in controlling dust erosion and is the

Investigating the size, shape and surface roughness dependence of polarization lidars with light-scattering computations on real mineral dust particles: Application to dust particles' external mixtures and dust mass concentration retrievals

Science.gov (United States)

Mehri, Tahar; Kemppinen, Osku; David, Grégory; Lindqvist, Hannakaisa; Tyynelä, Jani; Nousiainen, Timo; Rairoux, Patrick; Miffre, Alain

2018-05-01

Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass concentrations, polarization lidars are nowadays frequently used, with partitioning algorithms allowing to discern the contribution of mineral dust in two or three-component particle external mixtures. In this paper, we investigate the dependence of the retrieved dust backscattering (βd) vertical profiles with the dust particle size and shape. For that, new light-scattering numerical simulations are performed on real atmospheric mineral dust particles, having determined mineralogy (CAL, DOL, AGG, SIL), derived from stereogrammetry (stereo-particles), with potential surface roughness, which are compared to the widely-used spheroidal mathematical shape model. For each dust shape model (smooth stereo-particles, rough stereo-particles, spheroids), the dust depolarization, backscattering Ångström exponent, lidar ratio are computed for two size distributions representative of mineral dust after long-range transport. As an output, two Saharan dust outbreaks involving mineral dust in two, then three-component particle mixtures are studied with Lyon (France) UV-VIS polarization lidar. If the dust size matters most, under certain circumstances, βd can vary by approximately 67% when real dust stereo-particles are used instead of spheroids, corresponding to variations in the dust backscattering coefficient as large as 2 Mm- 1·sr- 1. Moreover, the influence of surface roughness in polarization lidar retrievals is for the first time discussed. Finally, dust mass-extinction conversion factors (ηd) are evaluated for each assigned shape model and dust mass concentrations are retrieved from polarization lidar measurements. From

Investigating respirable particulates (PM10) around the world's largest mercury mine, Almaden, Spain

Energy Technology Data Exchange (ETDEWEB)

Gibbons, W.; Jones, T. [Cardiff Univ., Cardiff, Wales (United Kingdom). Dept. of Earth Sciences; Moreno, T.; Richards, R. [Cardiff Univ., Cardiff, Wales (United Kingdom). School of Biosciences; Higueras, P. [Almaden Univ. of Castilla-La Mancha, Almaden (Spain). Dept. of Geological Engineering

2003-07-01

The Almaden area in Spain has been mined for mercury since pre-Roman days. There is no evidence for significant contamination of the groundwater supply, since the lack of pyrite in the mercury deposits has prevented the formation of acid mine drainage. However, the main recognized environmental problem related to mercury mining has been the progressive poisoning of workers who are in direct contact with mercury vapours. This paper presents results of a study in which dust samples were collected from former mining and urban locations around Almaden. The samples were processed to extract their fine, respirable fraction. Mining activities have left contaminated ground, which under semi-arid conditions has created respirable mercury-bearing dusts. In some places the ground is severely contaminated with mercury as cinnabar and as schuetteite. Some of the contaminated areas are used for livestock grazing and growing plants for human consumption. A higher incidence of mercury-bearing particles is found in the finer fraction. The sizes of the mercury-bearing resuspended particles at all sites varies from inhalable dust, through respirable dust, to fine and ultrafine size capable of reaching the deepest levels of the lung alveoli. The most significant contamination is associated with old processing plants. Dust samples collected from Almaden, a town of 6,500 inhabitants, were found to contain significant amounts of respirable mercury-bearing aerosols.

GPK helmets protecting from gas and dusts

Energy Technology Data Exchange (ETDEWEB)

Il' inskii, Eh.G.; Kogan, Yu.A.; Mazanenko, V.P.

1983-08-01

The GPK protective helmet with an integrated respirator system protecting a miner's respiratory system and eyes from gases and dusts is described. The system uses compressed air from the mine compressed air system. Air is supplied to the respirator by an elastic rubber pipe to 30 m long. The air cools the miner's head under the helmet and passes between a protective shield and the miner's face protecting eyes and the respiratory system. Air supply ranges from 100 to 150 l/min. The air supplied to the respirator is cleaned by a filter. The GPK system weighs 1.2 kg. The system has been tested under laboratory conditions and in two coal mines under operational conditions at longwall faces and during mine drivage. Tests showed that the GPK guarantees efficient cooling and protection from dust. Design of the GPK helmet with a respirator is shown in two schemes. Technical specifications of the system are given.

Using proximate analysis to characterize airborne dust generation from bituminous coals

Energy Technology Data Exchange (ETDEWEB)

Page, S.J.; Organiscak, J.A.

2005-11-01

Prolonged exposure to airborne respirable coal dust is responsible for coal workers pneumoconiosis (CWP), commonly called black lung. Health research studies have identified that the prevalence and severity of CWP are directly related to both the amount of dust exposure and the coal rank. The amount of airborne respirable dust (ARD) smaller than 10 micrometers generated from breakage of different coals varies widely. To investigate the cause, researchers for the National Institute for Occupational Safety and Health (NIOSH) have conducted experiments to identify the causes of airborne respirable dust liberation. Laboratory crushing experiments were conducted on a range of low to high volatile bituminous coals from eight mines. The results indicate that the proximate analysis of a coal sample can provide a very good indicator of the potential for a dust problem. For application to the coal mining, processing, and utilization industries, data from 977 US coal seams compiled by the Department of Energy (DoE) has been used to calculate this dust generation potential from an equation based on the NIOSH measured data. A simple procedure for this calculation is provided. 1 fig.

Characterization of airborne float coal dust emitted during continuous mining, longwall mining and belt transport.

Science.gov (United States)

Shahan, M R; Seaman, C E; Beck, T W; Colinet, J F; Mischler, S E

2017-09-01

Float coal dust is produced by various mining methods, carried by ventilating air and deposited on the floor, roof and ribs of mine airways. If deposited, float dust is re-entrained during a methane explosion. Without sufficient inert rock dust quantities, this float coal dust can propagate an explosion throughout mining entries. Consequently, controlling float coal dust is of critical interest to mining operations. Rock dusting, which is the adding of inert material to airway surfaces, is the main control technique currently used by the coal mining industry to reduce the float coal dust explosion hazard. To assist the industry in reducing this hazard, the Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health initiated a project to investigate methods and technologies to reduce float coal dust in underground coal mines through prevention, capture and suppression prior to deposition. Field characterization studies were performed to determine quantitatively the sources, types and amounts of dust produced during various coal mining processes. The operations chosen for study were a continuous miner section, a longwall section and a coal-handling facility. For each of these operations, the primary dust sources were confirmed to be the continuous mining machine, longwall shearer and conveyor belt transfer points, respectively. Respirable and total airborne float dust samples were collected and analyzed for each operation, and the ratio of total airborne float coal dust to respirable dust was calculated. During the continuous mining process, the ratio of total airborne float coal dust to respirable dust ranged from 10.3 to 13.8. The ratios measured on the longwall face were between 18.5 and 21.5. The total airborne float coal dust to respirable dust ratio observed during belt transport ranged between 7.5 and 21.8.

African Dust Transport Captured by Rare Earth Elemental Concentrations in Coral Microatolls

Science.gov (United States)

Ouellette, G., Jr.; DeLong, K.; Herrmann, A.; Huang, C. Y.; Shen, C. C.

2017-12-01

Winds are integral components of the climate system; unfortunately, windsare also among the climate variables that are most difficult to study prior to the instrumentalrecord. Paleoclimatologists use sedimentary dust records (e.g., lake and ocean cores) tounderstand past wind circulation conditions; however, these types of records typically are notamenable to sub-annual interpretation due to their limited temporal resolution. Here wedeveloped a coral-based dust-wind proxy to overcome these temporal limitations by usingtrace (nmol/mol) rare earth elemental concentrations recorded in the skeletons of coralmicroatolls. The rare earth elements (REE; the lanthanides as well as scandium and yttrium)behave similarly in geologic and geochemical systems, and have served as useful proxies ofgeological processes in both deep and shallow time. Corals incorporate REE as they deposittheir exoskeletons that extend incrementally with time forming annual density band couplets.Coral microatolls grow at or near the sea surface, where coral REE concentrations are mostsensitive to dust deposition. Our study site off the west coast of Haiti is down stream of light-REE depleted bedrock whereas REE in African dust, transported by the easterly trade winds,reflect average crustal abundances. This unique "upstream" source signature allows forterrestrial contamination of the dust-wind signal to be ruled out. Light REE concentrations (esp.Nd and Pr) demonstrate an order of magnitude increase within coral aragonite coincident withmajor African dust plume events throughout the past decade, with Nd/Ca and Pr/Ca increasingfrom an average of 27 nmol/mol to an average 144 nmol/mol and an average of 5 nmol/mol toan average of 37 nmol/mol, respectively, during major African dust plume events. Monthly-resolved REE analysis shows these REE peaks coincide with the summer dust season rather thanHaiti's two wet seasons in spring and autumn. Regression of our coral REE dust proxy tosatellite records of

Toxicity of lunar dust assessed in inhalation-exposed rats.

Science.gov (United States)

Lam, Chiu-wing; Scully, Robert R; Zhang, Ye; Renne, Roger A; Hunter, Robert L; McCluskey, Richard A; Chen, Bean T; Castranova, Vincent; Driscoll, Kevin E; Gardner, Donald E; McClellan, Roger O; Cooper, Bonnie L; McKay, David S; Marshall, Linda; James, John T

2013-10-01

Humans will again set foot on the moon. The moon is covered by a layer of fine dust, which can pose a respiratory hazard. We investigated the pulmonary toxicity of lunar dust in rats exposed to 0, 2.1, 6.8, 20.8 and 60.6 mg/m(3) of respirable-size lunar dust for 4 weeks (6 h/day, 5 days/week); the aerosols in the nose-only exposure chambers were generated from a jet-mill ground preparation of a lunar soil collected during the Apollo 14 mission. After 4 weeks of exposure to air or lunar dust, groups of five rats were euthanized 1 day, 1 week, 4 weeks or 13 weeks after the last exposure for assessment of pulmonary toxicity. Biomarkers of toxicity assessed in bronchoalveolar fluids showed concentration-dependent changes; biomarkers that showed treatment effects were total cell and neutrophil counts, total protein concentrations and cellular enzymes (lactate dehydrogenase, glutamyl transferase and aspartate transaminase). No statistically significant differences in these biomarkers were detected between rats exposed to air and those exposed to the two low concentrations of lunar dust. Dose-dependent histopathology, including inflammation, septal thickening, fibrosis and granulomas, in the lung was observed at the two higher exposure concentrations. No lesions were detected in rats exposed to ≤6.8 mg/m(3). This 4-week exposure study in rats showed that 6.8 mg/m(3) was the highest no-observable-adverse-effect level (NOAEL). These results will be useful for assessing the health risk to humans of exposure to lunar dust, establishing human exposure limits and guiding the design of dust mitigation systems in lunar landers or habitats.

Determinants of dust exposure in tunnel construction work.

Science.gov (United States)

Bakke, Berit; Stewart, Patricia; Eduard, Wijnand

2002-11-01

In tunnel construction work, dust is generated from rock drilling, rock bolting, grinding, scaling, and transport operations. Other important dust-generating activities are blasting rock and spraying wet concrete on tunnel walls for strength and finishing work. The aim of this study was to identify determinants of dust exposure in tunnel construction work and to propose control measures. Personal exposures to total dust, respirable dust, and alpha-quartz were measured among 209 construction workers who were divided into 8 job groups performing similar tasks: drill and blast workers, shaft drilling workers, tunnel boring machine workers, shotcreting operators, support workers, concrete workers, outdoor concrete workers, and electricians. Information on determinants was obtained from interviewing the workers, observation by the industrial hygienist responsible for the sampling, and the job site superintendent. Multivariate regression models were used to identify determinants associated with the dust exposures within the job groups. The geometric mean exposure to total dust, respirable dust, and alpha-quartz for all tunnel workers was 3.5 mg/m(3) (GSD = 2.6), 1.2 mg/m(3) (GSD = 2.4), and 0.035 mg/m(3) (GSD = 5.0), respectively. A total of 15 percent of the total dust measurements, 5 percent of the respirable dust, and 21 percent of the alpha-quartz exceeded the Norwegian OELs of 10 mg/m(3), 5 mg/m(3), and 0.1 mg/m(3), respectively. Job groups with highest geometric mean total dust exposure were shotcreting operators (6.8 mg/m(3)), tunnel boring machine workers (6.2 mg/m(3)), and shaft drilling workers (6.1 mg/m(3)). The lowest exposed groups to total dust were outdoor concrete workers (1.0 mg/m(3)), electricians (1.4 mg/m(3)), and support workers (1.9 mg/m(3)). Important determinants of exposure were job group, job site, certain tasks (e.g., drilling and scaling), the presence of a cab, and breakthrough of the tunnel. The use of ventilated, closed cabs appeared to be

Impact of needle age on the response of respiration in Scots pine to long-term elevation of carbon dioxide concentration and temperature

International Nuclear Information System (INIS)

Zha, T.; Ryyppo, A.; Kellomaki, S.; Wang, K-Y.

2002-01-01

The effects of needle age, elevated carbon dioxide and temperature on needle respiration in Scots pine was studied during a four-year period. Results showed that respiration rates and specific leaf area decreased in elevated atmospheric carbon dioxide concentration relative to ambient conditions, but increased in elevated temperature and when elevated atmospheric carbon dioxide and elevated temperature were combined. Starch and soluble sugar concentrations for a given needle age increased in elevated carbon dioxide, but decreased slightly under combined elevated temperature and elevated carbon dioxide conditions. Respiration rate and specific leaf area were highest in current year needles in all treatment modes. All treatment modes enhanced the difference in respiration between current year and older needles relative to ambient conditions. Carbohydrate concentration or specific leaf area remained unchanged in response to any treatment. Under ambient conditions the temperature coefficient of respiration increased slightly in elevated carbon dioxide regardless of age, however, there was significant decline at elevated temperature as well as when both carbon dioxide concentration and temperature were elevated, indicating acclimation of respiration to temperature. 48 refs., 2 tabs., 7 figs

Response of needle dark respiration of Pinus koraiensis and Pinus sylvestriformis to elevated CO2 concentra-tions for four growing seasons’ exposure

Institute of Scientific and Technical Information of China (English)

2007-01-01

The long-term effect of elevated CO2 concentrations on needle dark respiration of two coniferous spe- cies—Pinus koraiensis and Pinus sylvestriformis on the Changbai Mountain was investigated using open-top chambers. P. koraiensis and P. sylvestriformis were exposed to 700, 500 μmol·mol-1 CO2 and ambient CO2 (approx. 350 μmol·mol-1) for four growing seasons. Needle dark respiration was meas- ured during the second, third and fourth growing seasons’ exposure to elevated CO2. The results showed that needle dark respiration rate increased for P. koraiensis and P. sylvestriformis grown at elevated CO2 concentrations during the second growing season, could be attributed to the change of carbohydrate and/or nitrogen content of needles. Needle dark respiration of P. koraiensis was stimu- lated and that of P. sylvestriformis was inhibited by elevated CO2 concentrations during the third growing season. Different response of the two tree species to elevated CO2 mainly resulted from the difference in the growth rate. Elevated CO2 concentrations inhibited needle dark respiration of both P. koraiensis and P. sylvestriformis during the fourth growing season. There was consistent trend be- tween the short-term effect and the long-term effect of elevated CO2 on needle dark respiration in P. sylvestriformis during the third growing season by changing measurement CO2 concentrations. How- ever, the short-term effect was different from the long-term effect for P. koraiensis. Response of dark respiration of P. koraiensis and P. sylvestriformis to elevated CO2 concentrations was related to the treatment time of CO2 and the stage of growth and development of plant. The change of dark respiration for the two tree species was determined by the direct effect of CO2 and long-term acclimation. The prediction of the long-term response of needle dark respiration to elevated CO2 concentration based on the short-term response is in dispute.

Exposure to high glutamate concentration activates aerobic glycolysis but inhibits ATP-linked respiration in cultured cortical astrocytes.

Science.gov (United States)

Shen, Yao; Tian, Yueyang; Shi, Xiaojie; Yang, Jianbo; Ouyang, Li; Gao, Jieqiong; Lu, Jianxin

2014-08-01

Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd.

Demonstration of a dust control system for boom-type roadheader. Open-file report September 1979-July 1981

International Nuclear Information System (INIS)

Burnett, M.; Pokora, R.J.; Muldoon, T.

1981-09-01

This program was initiated by the Bureau of Mines to quantify the respirable dust problem caused by the use of roadheaders in underground metal-nonmetal mines with special emphasis on this problem in uranium mines. The objective was to develop methods or equipment to alleviate respirable dust and to implement a solution in a mine. Attempts to quantify the dust problem were made by a survey of MSHA records, a survey of State nine enforcement agencies, a survey of mine records, and dust measurements taken at two mines using roadheaders. The results are not conclusive because of limited and sometimes less than useful data; however, the study does indicate that a serious dust problem could and may exist. The report discusses the available data concerning respirable dust problems and presents a solution that can potentially help to solve the problem. The solution requires the use of blowing ventilation, onboard dust extraction at the source, filtration, and continued continued use of water sprays

Modeling of surface dust concentrations using neural networks and kriging

Science.gov (United States)

Buevich, Alexander G.; Medvedev, Alexander N.; Sergeev, Alexander P.; Tarasov, Dmitry A.; Shichkin, Andrey V.; Sergeeva, Marina V.; Atanasova, T. B.

2016-12-01

Creating models which are able to accurately predict the distribution of pollutants based on a limited set of input data is an important task in environmental studies. In the paper two neural approaches: (multilayer perceptron (MLP)) and generalized regression neural network (GRNN)), and two geostatistical approaches: (kriging and cokriging), are using for modeling and forecasting of dust concentrations in snow cover. The area of study is under the influence of dust emissions from a copper quarry and a several industrial companies. The comparison of two mentioned approaches is conducted. Three indices are used as the indicators of the models accuracy: the mean absolute error (MAE), root mean square error (RMSE) and relative root mean square error (RRMSE). Models based on artificial neural networks (ANN) have shown better accuracy. When considering all indices, the most precision model was the GRNN, which uses as input parameters for modeling the coordinates of sampling points and the distance to the probable emissions source. The results of work confirm that trained ANN may be more suitable tool for modeling of dust concentrations in snow cover.

The solubility of thorium and uranium from respirable monazite bearing dust in simulated lung and gut fluids

International Nuclear Information System (INIS)

Twining, J.; McGlinn, P.; Hart, K.

1993-01-01

The accurate assessment of the radiological dose to workers in the mineral sands industry requires information on the human bio-availability of thorium and uranium from monazite bearing respirable dust. The results of a short-term test to determine some of the solubility characteristics of these radionuclides are presented, together with a discussion on the optimum methods which may be applied to longer term studies. The solubility of thorium and uranium were found to be generally less than that of the parent monazite bearing dust in simulated lung and gut fluids over the one month extraction period. In particular, thorium was up to two orders of magnitude less soluble than its host mineral matrix. Assuming that the conservative nature of these radioactive constituents can be extrapolated to longer term exposures, these results imply that radiological dose estimates to the lung should be increased. Solubility of both elements was proportional to particle size. An exponential increase in solubility with decreasing diameter was observed, which implies a time variable solubility. There was also some indication of preferential solubility of radium progeny in both decay series. These factors may have to be accounted for in model estimates of committed dose. 16 refs., 4 tabs., 2 figs

Evaluating Ice Nucleating Particle Concentrations From Prognostic Dust Minerals in an Earth System Model

Science.gov (United States)

Perlwitz, J. P.; Knopf, D. A.; Fridlind, A. M.; Miller, R. L.; Pérez García-Pando, C.; DeMott, P. J.

2016-12-01

The effect of aerosol particles on the radiative properties of clouds, the so-called, indirect effect of aerosols, is recognized as one of the largest sources of uncertainty in climate prediction. The distribution of water vapor, precipitation, and ice cloud formation are influenced by the atmospheric ice formation, thereby modulating cloud albedo and thus climate. It is well known that different particle types possess different ice formation propensities with mineral dust being a superior ice nucleating particle (INP) compared to soot particles. Furthermore, some dust mineral types are more proficient INP than others, depending on temperature and relative humidity.In recent work, we have presented an improved dust aerosol module in the NASA GISS Earth System ModelE2 with prognostic mineral composition of the dust aerosols. Thus, there are regional variations in dust composition. We evaluated the predicted mineral fractions of dust aerosols by comparing them to measurements from a compilation of about 60 published literature references. Additionally, the capability of the model to reproduce the elemental composition of the simulated dusthas been tested at Izana Observatory at Tenerife, Canary Islands, which is located off-shore of Africa and where frequent dust events are observed. We have been able to show that the new approach delivers a robust improvement of the predicted mineral fractions and elemental composition of dust.In the current study, we use three-dimensional dust mineral fields and thermodynamic conditions, which are simulated using GISS ModelE, to calculate offline the INP concentrations derived using different ice nucleation parameterizations that are currently discussed. We evaluate the calculated INP concentrations from the different parameterizations by comparing them to INP concentrations from field measurements.

Contrasting respirable quartz and kaolin retention of lecithin surfactant and expression of membranolytic activity following phospholipase A2 digestion.

Science.gov (United States)

Wallace, W E; Keane, M J; Mike, P S; Hill, C A; Vallyathan, V; Regad, E D

1992-11-01

Respirable-sized quartz, a well-established fibrogenic mineral dust, is compared with kaolin in erythrocyte hemolysis assays after treatment with saline dispersion of dipalmitoyl phosphatidylcholine, a primary phospholipid component of pulmonary surfactant. Both dusts are rendered inactive after treatment, but the membranolytic activity is partly to fully restored after treatment with phospholipase A2, an enzyme normally associated with cellular plasma membranes and lysosomes. Phospholipid-coated dusts were incubated for periods of 2-72 h at a series of applied enzyme concentrations, and the adsorbed lipid species and hemolytic activity were quantitated at each time for both dusts. Surfactant was lost more readily from quartz than from kaolin, with consequent more rapid restoration of mineral surface hemolytic activity for quartz. Interactions of surfactant and mineral surface functional groups responsible for the mineral-specific rate differences, and implications for determining the mineral surface bioavailability of silica and silicate dusts, are discussed.

Saharan dust, climate variability, and asthma in Grenada, the Caribbean.

Science.gov (United States)

Akpinar-Elci, Muge; Martin, Francis E; Behr, Joshua G; Diaz, Rafael

2015-11-01

Saharan dust is transported across the Atlantic and interacts with the Caribbean seasonal climatic conditions, becoming respirable and contributing to asthma presentments at the emergency department. This study investigated the relationships among dust, climatic variables, and asthma-related visits to the emergency room in Grenada. All asthma visits to the emergency room (n = 4411) over 5 years (2001-2005) were compared to the dust cover and climatic variables for the corresponding period. Variation in asthma was associated with change in dust concentration (R(2) = 0.036, p asthma was positively correlated with rainfall (R(2) = 0.055, p asthma visits were inversely related to mean sea level pressure (R(2) = 0.123, p = 0.006) and positively correlated with relative humidity (R(2) = 0.593, p = 0.85). Saharan dust in conjunction with seasonal humidity allows for inhalable particulate matter that exacerbates asthma among residents in the Caribbean island of Grenada. These findings contribute evidence suggesting a broader public health impact from Saharan dust. Thus, this research may inform strategic planning of resource allocation among the Caribbean public health agencies.

Large-scale coherent structures of suspended dust concentration in the neutral atmospheric surface layer: A large-eddy simulation study

Science.gov (United States)

Zhang, Yangyue; Hu, Ruifeng; Zheng, Xiaojing

2018-04-01

Dust particles can remain suspended in the atmospheric boundary layer, motions of which are primarily determined by turbulent diffusion and gravitational settling. Little is known about the spatial organizations of suspended dust concentration and how turbulent coherent motions contribute to the vertical transport of dust particles. Numerous studies in recent years have revealed that large- and very-large-scale motions in the logarithmic region of laboratory-scale turbulent boundary layers also exist in the high Reynolds number atmospheric boundary layer, but their influence on dust transport is still unclear. In this study, numerical simulations of dust transport in a neutral atmospheric boundary layer based on an Eulerian modeling approach and large-eddy simulation technique are performed to investigate the coherent structures of dust concentration. The instantaneous fields confirm the existence of very long meandering streaks of dust concentration, with alternating high- and low-concentration regions. A strong negative correlation between the streamwise velocity and concentration and a mild positive correlation between the vertical velocity and concentration are observed. The spatial length scales and inclination angles of concentration structures are determined, compared with their flow counterparts. The conditionally averaged fields vividly depict that high- and low-concentration events are accompanied by a pair of counter-rotating quasi-streamwise vortices, with a downwash inside the low-concentration region and an upwash inside the high-concentration region. Through the quadrant analysis, it is indicated that the vertical dust transport is closely related to the large-scale roll modes, and ejections in high-concentration regions are the major mechanisms for the upward motions of dust particles.

Calculation of risk for workers in dust working site

Directory of Open Access Journals (Sweden)

Geldová Erika

2004-03-01

Full Text Available The fibrogeneous dust is considered as a specific harmful substance in the mine working site. Such kind of dust cumulates in lungs and this fact usually results in lungs dusting, so - called pneumoconiosis. Thus, dustiness risk poses a probability of lungs damage by pneumoconiosis. For the calculation of dustiness risk it is needed to know the following data: the value of average dustiness kC in the working site per a definite time period, the dispersivity of dust “D” (it determines a portion of dust particles with a diameter under 5 µm, so - called respirable particles and the percentage content of quartz Qr in the respirable grain size fraction.The contribution presents the calculation of dustiness risk “R” according to the equation (1, where “R” is in percentage, “ša” is the analytically specific harmfulness and “KDc” is the total cumulative dust dose received by worker in time of its dust exposure.The total cumulative dust dose is calculated on the basis of the equation (4, where “kc” is the average dust concentration in the assessed time period, t–time of exposure, V –average amount of air inspired by exposed worker per time unit ( standardized on the value of 1,2 m3h-1,10-6-recalculation from mg to kg for “KDc”.If the values of “Qr”, “D” and “kc” during the worker exposure on a definite workplace are constant, the dustiness risk “R” is calculated according to the equation (1 and (5 respectively. In the case of “n” time intervals in that the values “Qr”, “D” and “kc” are known the dustiness risk “R” is calculated according to the equation (7. The total personal risk of worker is given by the equation (8.Conclusively, the influence of parameters change namely “Qr”, “D” and “kc” on the value of dustiness risk per equal time period is reported.

An analysis of the correlation between dust storms in Korea and 137Cs nuclide concentration

International Nuclear Information System (INIS)

Choi, Soo-won; Kim, Jeong-hun; Shin, Sang-hwa; Hwang, Joo-ho

2008-01-01

Dust storms occur in Korea during spring time when fine dust is blown in from the far western regions of western China and Mongolia. A fine powdery dust is blown up into the sky and enters the upper reaches of the atmosphere where it is carried easterly across China then slowly falls to the ground on the Korean peninsula and Japan. The dust originates mostly in the Gobi dessert of China, as well as the yellow earth regions in the middle and upper streams of the Yellow river in China. Previous studies on dust storms have been limited to following or estimating their courses, distribution and frequency, or distribution of the heavy metals they transmit. However, since radionuclides exist in the dust, they must also exist in the dust storms. In this study, we analyzed the correlation of :1 37 Cs nuclide concentration based on a count of annual dust storm occurrence in the city of Suwon, South Korea and assessed seasonal differences of 137 Cs nuclide concentration

Field evaluation of air-blocking shelf for dust control on blasthole drills

Energy Technology Data Exchange (ETDEWEB)

J. Drew Potts; W. Randolph Reed [Office of Mine Safety and Health Research, NIOSH, Pittsburgh, PA (United States). Dust Control, Ventilation, and Toxic Substance Branch

2011-03-15

In previous studies, an air-blocking shelf has been shown to be successful in reducing respirable dust leakage from the drill shroud in a laboratory setting. Dust reductions of up to 81% were achieved with the shelf under operating conditions consisting of a 1.9:1 collector-to-bailing airflow ratio and a 5.1-cm gap between the shroud and ground. Recent research focused on evaluating the shelf on two actual operating blasthole drills, in much more severe environments. In the field, the shelf reduced dust levels in the areas surrounding one operating blasthole drill by 70%. Dust reductions measured in the immediate vicinity of the shroud were reduced by 66% at one mine and 81% at the other mine. These field tests confirm that the air-blocking shelf is useful for reducing respirable dust generation from blasthole drills.

Intrapulmonary reactions of workers exposed to dust and ozone

Energy Technology Data Exchange (ETDEWEB)

Tsunoda, T; Nakadate, T; Sakurai, M; Sakurai, Y

1984-01-01

Forty-one dust-and-ozone-exposed and 37 nonexposed workers, belonging to the Research and Development Division of a photo-copier manufacturing industry, were examined to assess the effect of the exposure to carbon, iron and resin dust and ozone in the air of the work environment by means of questionnaires on their physical condition, smoking habits and exposure history by interview, chest X-rays, testing of ventilatory functions, transcutaneous PO2 (tcPO2) test and H2O2-induced hemolysis test. The following results were obtained. Respirable dust concentrations in the air of the work place were 0.1-1.0 mg/m3, total dust concentrations 0.2-2.0 mg/m3, and ozone concentrations 0.004-0.06 ppm (0.008-0.12 mg/m3). According to the Japanese Classification of Radiographs of Pneumoconioses, the exposed workers showed a higher rate of profusion 0/1 and over, and category 1 and over (1/0 and over) than the nonexposed workers. Ventilatory function testing revealed no difference between exposed workers and nonexposed workers, but small airway narrowing was suspected in smoking workers in comparison with nonsmoking workers. Transcutaneous PO2 showed no difference between exposed and nonexposed workers, between smoking and nonsmoking workers, and between any of the paired six combinations out of the four groups of workers, i.e., nonsmoking and nonexposed, nonsmoking and exposed, smoking and nonexposed, and smoking and exposed. It was estimated by H2O2-induced hemolysis test that smoking and/or dust exposure, especially long-term exposure, gave rise to aggravation of fragility of the erythrocyte membrane by lipid peroxidation with ozone or active oxygen produced by the reaction of dust and alveolar macrophages.

The effect of mineral dust transport on PM10 concentrations and physical properties in Istanbul during 2007-2014

Science.gov (United States)

Flores, Rosa M.; Kaya, Nefel; Eşer, Övgü; Saltan, Şehnaz

2017-11-01

Mineral dust is the most significant source of natural particulate matter. In urban regions, where > 50% of the world population is currently living, local emissions of particulate matter are further aggravated by mineral dust loadings from deserts. The megacity of Istanbul is located in an area sensitive to local pollution due to transportation (i.e., private cars, public transportation, aircrafts, ships, heavy diesel trucks, etc.), industrial emissions, residential heating, and long-range transport from Europe, Asia, and deserts. In this work, the effect of desert dust transport on PM10 concentrations and physical properties was investigated for the period of 2007-2014 in the touristic area of Aksaray, Istanbul. The Dust Regional Atmospheric Model (DREAM8b) was used to predict dust loading in Istanbul during dust transport events. Variations on surface PM10 concentrations were investigated according to seasons and during dust transport events. Cluster analysis of air mass backward trajectories was useful to understand frequency analysis and air mass trajectory dependence of PM10 concentrations on dust loadings. The effect of desert dust transport on aerosol optical depths was also investigated. It was observed that PM10 concentrations exceeded the air quality standard of 50 μg m- 3 50% of the time during the study period. The largest number of exceedances in air quality standard occurred during the spring and winter seasons. Approximately 40-60% of the dust loading occurs during the spring. Desert dust and non-desert dust sources contribute to 22-72% and 48-81% of the ground-level PM10 concentrations in Aksaray, Istanbul during the study period. Averaged AOD observed during dust transport events in spring and summer ranged 0.35-0.55. Cluster analysis resolved over 82% the variability of individual air mass backward trajectories into 5 clusters. Overall, air masses arriving to Istanbul at 500 m are equally distributed into northern (52%) and southern (48

Effects of low concentrations of sulfur dioxide on net photosynthesis and dark respiration of Vicia faba

Energy Technology Data Exchange (ETDEWEB)

Black, V J; Unsworth, M H

1979-01-01

Rates of net photosynthesis, P/sub N/, and dark respiration of Vicia faba plants were measured in the laboratory in clean air and in air containing up to 175 parts 10/sup -9/ (500 ..mu..g m/sup -3/) SO/sub 2/. At all SO/sub 2/ concentrations exceeding 35 parts 10/sup -9/, P/sub N/ was inhibited compared with clean air. At light saturation, the magnitude of inhibition depended on SO/sub 2/ concentration but at low irradiances the inhibition was independent of concentration. Dark respiration rates increased substantially, independent of concentration. When exposures continued for up to 3 days, P/sub N/ returned to clean air values about 1 h after fumigation ceased: dark respiration recovered after one photoperiod. There were no visible injuries. Reviewing possible mechanisms responsible for the inhibition of P/sub N/, it is suggested that SO/sub 2/ competes with CO/sub 2/ for binding sites in RuBP carboxylase. Analysis of resistance analogues demonstrates that SO/sub 2/ altered both stomatal and internal (residual) resistances. A model of crop photosynthesis shows the implications of the observed responses for the growth of field crops in which plants are assumed to respond like laboratory plants. Photosynthesis of the crop would be less sensitive than that of individual plants to SO/sub 2/ concentration. Daily dry matter accumulation of hypothetical polluted crops would be substantially less than clean air values but would vary relatively little with SO/sub 2/ concentration. It is concluded that physiological bases exist to account for observed reductions in growth of plants at very low SO/sub 2/ concentrations, and that thresholds for plant responses to SO/sub 2/ require reassessment. 30 references, 5 figures, 1 table.

Quantification of dust generating sources in gold and platinum mines.

CSIR Research Space (South Africa)

Biffi, M

2003-03-01

Full Text Available of workers from harmful respirable dust as well as projections for future work. Summary of dust levels from test mines Dust Levels [mg/m³] Mine Mine Type Dust Source Min Max Avg Crystalline Silica [%] Intake 0.09 1.57 0.46 Tips 0.23 0.65 0... ? The movement of people and rolling stock along haulages, travelling ways and production areas liberating settled dust, ? Rock crushing. ? Screening, grinding, milling and pulverising of the ore during processing. ? Backfill placement. Good practice...

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

International Nuclear Information System (INIS)

Simon, Edina; Braun, Mihaly; Vidic, Andreas; Bogyo, David; Fabian, Istvan; Tothmeresz, Bela

2011-01-01

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. - Highlights: → We studied the elements in dust and leaves along an urbanization gradient, Austria. → We analysed 19 elements: Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Na, P, Pb, S, Sr and Zn. → Elemental concentrations were higher in urban area than in the rural area. → Studied areas were separated by CDA based on the elemental concentrations. → Dust and leaves can be useful for monitoring the environmental load. - Studying the elements (Al, Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, Zn) in dust and leaves along an urbanization gradient in Wien, Austria we found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for Al, Ba, Fe, Pb, P and Se, and concentrations of leaves were significantly higher in urban than in rural area for Mn and Sr.

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

Energy Technology Data Exchange (ETDEWEB)

Simon, Edina, E-mail: edina.simon@gmail.com [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Braun, Mihaly [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Vidic, Andreas [Department fuer Naturschutzbiologie, Vegetations- und Landschaftsoekologie, Universitat Wien, Althanstrasse 14, 1090 Wien (Austria); Bogyo, David [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Fabian, Istvan [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Tothmeresz, Bela [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary)

2011-05-15

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. - Highlights: > We studied the elements in dust and leaves along an urbanization gradient, Austria. > We analysed 19 elements: Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Na, P, Pb, S, Sr and Zn. > Elemental concentrations were higher in urban area than in the rural area. > Studied areas were separated by CDA based on the elemental concentrations. > Dust and leaves can be useful for monitoring the environmental load. - Studying the elements (Al, Ba, Ca, Cu, Fe, K, Mg, Na, P, S, Sr, Zn) in dust and leaves along an urbanization gradient in Wien, Austria we found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for Al, Ba, Fe, Pb, P and Se, and concentrations of leaves were significantly higher in urban than in rural area for Mn and Sr.

Pulmonary inflammation and crystalline silica in respirable coal ...

Indian Academy of Sciences (India)

Unknown

This study demonstrates dose-response relationships between respirable crystalline silica in coal mine dust and pulmonary inflammation, antioxidant production, and radiographic small opacities. [Kuempel E D, Attfield M D, Vallyathan V, Lapp N L, Hale J M, Smith R J and Castranova V 2003 Pulmonary inflammation and ...

Dust and radon: the legal implications

International Nuclear Information System (INIS)

Van Sittert, J.M.O.

1990-01-01

It is known that radon gas is not generally considered to be a major problem when encountered in the working environment. However, in its process of decay, a series of four short lived daughter products are formed. In a dust-laden atmosphere these daughter products, which are ionized readily, attach to the particulate material and when inhaled are deposited in the alveoli of the lungs. Therefore, if respirable dust is controlled, the effects of radon daughters will also be minimized. The legal requirements for dust control in South Africa and their implications are discussed. 1 ill

The risk of pulmonary tuberculosis in underground copper miners in Zambia exposed to respirable silica: a cross-sectional study

Directory of Open Access Journals (Sweden)

Kingsley Ngosa

2016-08-01

Full Text Available Abstract Background Pulmonary tuberculosis (PTB among underground miners exposed to silica remains a global problem. Although well described in gold and coal mining, risk in other mining entities are not as well documented. This study aims to determine dust-related dose response risk for PTB among underground miners exposed to silica dust in Zambia's copper mines. Methods A cross sectional study of in-service miners (n = 357 was conducted at Occupational Health and Safety Institute (OHSI, Zambia. A systematic review of medical data over a 5-year period from assessments conducted by doctors at OHSI and statutory silica exposure data (n = 16678 from the Mine Safety Department (MSD were analysed. Lifetime cumulative exposure metrics were calculated. Multivariate logistic regression analysis was used to determine the association between PTB and lifetime exposure to silica, while adjusting for various confounders. Results The median respirable silica dust level was 0.3 mg/m3 (range 0.1–1.3. The overall prevalence of PTB was 9.5 % (n = 34. High cumulative respirable silica dust category showed a statistically significant association with PTB (OR = 6.4 (95 % CI 1. 8–23 and a significant trend of increasing disease prevalence with increasing cumulative respirable silica dust categories was observed (ptrend < 0.01. Smoking showed a statistically significant association with PTB with OR = 4.3 (95 % CI 1.9–9.9. Conclusions Our results demonstrate the association of increased risk for certified active TB with cumulative respirable dust in a dose related manner among this sample of copper miners. There is need to intensify dust control measures and incorporate anti-smoking interventions into TB prevention and control programmes in the mines.

Field trials of an electret based passive dust sampler in coal mines

Energy Technology Data Exchange (ETDEWEB)

Hemingway, M.A.; Brown, R.C.; Arthur, J. [Health and Safety Laboratory, Sheffield (United Kingdom)

1997-12-31

An electret-based passive dust sampler has been developed by the Health and Safety Laboratory, UK. The device consists of a small disc of electret (polymer holding a permanent electric charge) held between earthen plates, and it acts by attaching charged dust particles to itself. The device does not require a pump and its rate of sampling is independent of external air velocity, provided that the velocity exceeds a low limiting value. Experiments have been carried out in two coal mines. In each experiment two passive sampler were mounted alongside an MRE sampler at the statutory sampling point in the return roadway. Both passive samplers were mounted vertically but in one the plane of the electret was parallel to the air flow and in the other it was perpendicular. The result obtained from the first mine showed a good correlation between gravimetric estimates of dust concentration obtained with the passive samplers and respirable dust concentrations obtained with MRE. The correlation between the two sets of results at the second mine was not quite as good as those of the first, but was reasonable. In no instance was any significant difference observed between samples obtained from pairs of passive samples in different orientations. 8 refs., 5 figs., 2 tabs.

Evaluation of Dust Exposure among the Workers in Agricultural Industries in North-East India.

Science.gov (United States)

Dewangan, Krishna N; Patil, Mahesh R

2015-11-01

This study aims to quantify dust exposure among the workers in four different industrial settings: rice mills, flour mills, oil mills, and tea factories and to compare the obtained data with the permissible exposure limit (PEL) of Indian Union Ministry of Labour as well as to compare the dust exposure across activities and seasons. RespiCon(TM) particle sampler was used for collecting dust concentration in the breathing zone of the workers. In total, 149 workers participated in the study and 204 samples were collected. Samples were collected in the vicinity of different processing operations. Samples in the rice mills were collected for two consecutive years in two seasons; however samples from other industries were collected for 1 year. The results indicate that geometric mean (GM) of dust exposure was significantly (P workers are exposed to higher level of respirable dust as compared to the PEL, while total dust exposure to all the workers were higher than the PEL; thus, immediate reduction of dust exposure among the workers is necessary for preventing respiratory system impairment. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Quantitative detection of mass concentration of sand-dust storms via wind-profiling radar and analysis of Z- M relationship

Science.gov (United States)

Wang, Minzhong; Ming, Hu; Ruan, Zheng; Gao, Lianhui; Yang, Di

2018-02-01

With the aim to achieve quantitative monitoring of sand-dust storms in real time, wind-profiling radar is applied to monitor and study the process of four sand-dust storms in the Tazhong area of the Taklimakan Desert. Through evaluation and analysis of the spatial-temporal distribution of reflectivity factor, it is found that reflectivity factor ranges from 2 to 18 dBz under sand-dust storm weather. Using echo power spectrum of radar vertical beams, sand-dust particle spectrum and sand-dust mass concentration at the altitude of 600 ˜ 1500 m are retrieved. This study shows that sand-dust mass concentration reaches 700 μg/m3 under blowing sand weather, 2000 μg/m3 under sand-dust storm weather, and 400 μg/m3 under floating dust weather. The following equations are established to represent the relationship between the reflectivity factor and sand-dust mass concentration: Z = 20713.5 M 0.995 under floating dust weather, Z = 22988.3 M 1.006 under blowing sand weather, and Z = 24584.2 M 1.013 under sand-dust storm weather. The retrieval results from this paper are almost consistent with previous monitoring results achieved by former researchers; thus, it is implied that wind-profiling radar can be used as a new reference device to quantitatively monitor sand-dust storms.

Radiation, ventilation and dust studies at Agnew Lake mines

International Nuclear Information System (INIS)

Bigu, J.; Gangal, M.; Knight, G.; Regan, R.; Stefanich, W.

1980-08-01

Measurements of radon gas, radon and thoron decay products, ventilation, and aerosol (<= 0.13 μm) and respirable dust (<= 10 μm) concentrations were conducted at an underground uranium mine in the Agnew Lake, Ontario, area. Radon gas measurements were carried out with a radon gas continuous monitoring system, whereas the other variables were determined by grab-sampling techniques. Studies were conducted at three mine locations: a working stope, an exhaust area near the stope and a general intake area supplying fresh air to several stopes. Radiation and dust studies were carried out for different mining operations (mainly mucking and drilling) and environmental conditions. Underground barometric pressure did not seem to affect radon gas levels. No obvious effect on radiation and dust levels was readily observed nor could be correlated with underground meteorological data within the relatively narrow range the (meteorological) variables changed. Theoretical calculations for some radiation variables were done and compared with experimental values. Within the limitations of some of the calculations, overall fair agreement between experimental and theoretical data was found

Adaptation of the DP 50 dust meter for measuring dust content under isokinetic conditions

Energy Technology Data Exchange (ETDEWEB)

Vitek, J.; Novak, L.

1985-03-01

The DP 50 dust meter, developed by the Scientific Coal Research Institute Ostrava-Radvanice, is used for measuring dust content in the air in underground coal mines. Two versions of the system are used: a type developed in 1970 which is placed in a vertical position and used to measure the content of respirable coal particles in the air; and a type developed in 1983 for isokinetic measurement of dust content in the air. The latter is equipped with 8 cone-shaped adapters (with differing size and dimensions of the cone inlet adjusted to air flow rates from 0.25 to 8.00 m/s). Specifications of the 8 adapters are given in a table. The 1983 version of the DP 50 is placed in a horizontal position with the dust meter axis parallel to the direction of air flow ventilating a mine working. Recommendations for installation of dust meters in underground workings and effects of installation on measurement accuracy are discussed. 16 references.

Concentrations of polychlorinated biphenyls in soil and indoor dust associated with electricity generation facilities in Lagos, Nigeria.

Science.gov (United States)

Folarin, Bilikis Temitope; Abdallah, Mohamed Abou-Elwafa; Oluseyi, Temilola; Olayinka, Kehinde; Harrad, Stuart

2018-09-01

Concentrations of 7 indicator polychlorinated biphenyls (PCBs) were measured in dust and soil samples from 12 power stations collected over the two major seasons of the Nigerian climate. Median ƩPCB 7 concentrations in soil ranged from 2 ng/g for power station A to 220 ng/g for power station I; while those in dust ranged from 21 ng/g for power station L to 2200 ng/g for power station I. For individual congeners, median PCB concentrations ranged from 3.8 ng/g for PCB 101 to 52 ng/g for PCB 180 in dust, and  transmission > distribution). Congener patterns in dust and soil samples were compared using principal component analysis (PCA) with those in transformer oil samples from 3 of the power stations studied and with common PCB mixtures (Aroclors). This revealed congener patterns in soil were more closely related to that in the transformer oil than dust. Congener patterns in most samples were similar to Aroclor 1260. Concentrations of PCBs in soil samples close to the transformers significantly exceeded those in soil sampled further away. Copyright © 2018 Elsevier Ltd. All rights reserved.

Windows pollution problems of the dust concentration measurement based on scattering method

International Nuclear Information System (INIS)

Zhao Yanjun; Zhang Yongtao; Shi Xinyue; Xu Chuanlong; Wang Shimin

2009-01-01

The windows are separated the measurement system from the dust space in the light Scattering dust concentration measurement system. The windows are polluted unavoidably by the dust and the measurement error is produced. Based on the Mie Scattering theory, the measurement error is researched in this paper. The numerical simulation results show that the measurement error is related to the particles diameter distribution and the refractive index, but is independent of the particles average diameter. A novel photoelectricity sensor is developed in this paper in order to solve the measurement error by the windows pollution. The calculated method is brought out which can amend the measurement errors by the windows pollution and improve the measurement accuracy.

Root respiration in North American forests: Effects of nitrogen concentration and temperature across biomes

Science.gov (United States)

A.J. Burton; K.S. Pregitzer; R.W. Ruess; R.L. Hendrick; Mike F. Allen

2002-01-01

Root respiration rates have been shown to be correlated with temperature and root N concentration in studies of individual forest types or species, but it is not known how universal these relationships are across forest species adapted to widely different climatic and edaphic conditions. In order to test for broad, cross-species relationships, we measured fine root...

Urinary 1-hydroxypyrene concentrations in Chinese coke oven workers relative to job category, respirator usage, and cigarette smoking

Energy Technology Data Exchange (ETDEWEB)

Bo Chen; Yunping Hu; Lixing Zheng; Qiangyi Wang; Yuanfen Zhou; Taiyi Jin [Fudan University, Shanghai (China). School of Public Health

2007-09-15

1-Hydroxypyrene (1-OHP) is a biomarker of recent exposure to polycyclic aromatic hydrocarbons (PAHs). We investigated whether urinary 1-OHP concentrations in Chinese coke oven workers (COWs) are modulated by job category, respirator usage, and cigarette smoking. The present cross-sectional study measured urinary 1-OHP concentrations in 197 COWs from Coking plant I and 250 COWs from Coking plant II, as well as 220 unexposed referents from Control plant I and 56 referents from Control plant II. Urinary 1-OHP concentrations (geometric mean, {mu}mol/mol creatinine) were 5.18 and 4.21 in workers from Coking plants I and II, respectively. The highest 1-OHP levels in urine were found among topside workers including lidmen, tar chasers, and whistlers. Benchmen had higher 1-OHP levels than other workers at the sideoven. Above 75% of the COWs exceeded the recommended occupational exposure limit of 2.3 {mu}mol/mol creatinine. Respirator usage and increased body mass index (BMI) slightly reduced 1-OHP levels in COWs. Cigarette smoking significantly increased urinary 1-OHP levels in unexposed referents but had no effect in COWs. Chinese COWs, especially topside workers and benchmen, are exposed to high levels of PAHs. Urinary 1-OHP concentrations appear to be modulated by respirator usage and BMI in COWs, as well as by smoking in unexposed referents.

Open-air sprays for capturing and controlling airborne float coal dust on longwall faces

Science.gov (United States)

Beck, T.W.; Seaman, C.E.; Shahan, M.R.; Mischler, S.E.

2018-01-01

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. PMID:29348700

Open-air sprays for capturing and controlling airborne float coal dust on longwall faces.

Science.gov (United States)

Beck, T W; Seaman, C E; Shahan, M R; Mischler, S E

2018-01-01

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening.

Temperature sensitivity of soil respiration is dependent on readily decomposable C substrate concentration

Science.gov (United States)

Larionova, A. A.; Yevdokimov, I. V.; Bykhovets, S. S.

2007-06-01

Temperature acclimation of soil organic matter (SOM) decomposition is one of the major uncertainties in predicting soil CO2 efflux by the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006) based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax) and half- saturation constant (Ks) cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of the data obtained in the incubation experiments with forest and arable soils. Our data confirm the hypothesis and suggest that concentration of readily decomposable C substrate as glucose equivalent is an important factor controlling temperature sensitivity. The highest temperature sensitivity was observed when C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, explaining this phenomenon by changes in concentration of readily decomposable C substrate. It is worth noting that this pattern works regardless of the origin of C substrate: production by SOM decomposition, release into the soil by rhizodeposition, litter fall or drying-rewetting events.

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna.

Science.gov (United States)

Simon, Edina; Braun, Mihály; Vidic, Andreas; Bogyó, Dávid; Fábián, István; Tóthmérész, Béla

2011-05-01

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load. Copyright © 2011 Elsevier Ltd. All rights reserved.

Evaluation of respirable particle matter in gold mine tailings on the Witwatersrand

International Nuclear Information System (INIS)

Ojelede, M.E.; Annegarn, H.J.

2007-01-01

Within the Witwatersrand gold mining area of South Africa, wind-blown dust is a significant contributor to atmospheric air pollution brought to the fore with the reworking of old mine tailings. Approximately 40,000 hectares are covered with tailings in the Witwatersrand. Wind-erosion during late austral winter and early spring causes surfaces of these tailings to be exposed, particularly during higher wind speeds and in the absence of rainfall. Local residents complain as the surrounding areas experience unpleasant dust episodes. As a result of urban PM 10 and PM 2.5 respirable particulate matter, increased respiratory ailments, morbidity and mortality, and concerns about the health impacts of wind-blown mine tailings in South Africa have been reported. Since 1981, significant monitoring of dustfall has taken place on the Witwatersrand, however, characterization of the respirable fraction of gold mine tailings material and dustfall is lacking. This paper presented the results of a study that established the content of respirable particulate matter in exposed mine tailings and wind-blown dust, and their likely contributions to ambient air. The initial results of the particulate size distribution of material samples from tailings and dust deposits collected in ambient dustfall-monitors were provided. Particle size distributions from different deposit types include slimes and sand deposits, surface and core material, and wind-winnowed secondary deposits. Fractions of PM 10 in source and deposited material were also discussed. It was concluded that there was a significant fraction of PM 10 material in the mine tailings, and that further work to quantify the population exposure risk is needed. 11 refs., 1 tab., 6 figs

Choosing the right respirator

International Nuclear Information System (INIS)

Bidwell, J.

1997-01-01

Selecting respirators to help protect workers from airborne contaminants can be a confusing process. The consequences of selecting the incorrect respirator can be intimidating, and worker safety and health may be dramatically and irreparably affected if an inappropriate respirator is chosen. When used in the workplace, a formal respiratory protection program must be established covering the basic requirements outlined in the OSHA Respiratory Protection Standard (29 CFR 1910.134). Education and training must be properly emphasized and conducted periodically. Maintenance, cleaning, and storage programs must be established and routinely followed for reusable respirators. The process of establishing a respiratory protection program can be broken down into four basic steps: Identify respiratory hazards and concentrations; understand the contaminants effects on workers' health; select appropriate respiratory protection; and train in proper respirator use and maintenance. These four steps are the foundation for establishing a basic respirator protection program. Be sure to consult state and federal OSHA requirements to ensure that the program complies. Leading industrial respirator manufacturers should be able to assist with on-site training and education in this four-step process, in addition to helping employers train their workers and conduct respirator fit testing

Separation of mycotoxin-containing sources in grain dust and determination of their mycotoxin potential.

Science.gov (United States)

Palmgren, M S; Lee, L S

1986-01-01

Two distinct reservoirs of mycotoxins exist in fungal-infected cereal grains--the fungal spores and the spore-free mycelium-substrate matrix. Many fungal spores are of respirable size and the mycelium-substrate matrix can be pulverized to form particles of respirable size during routine handling of grain. In order to determine the contribution of each source to the level of mycotoxin contamination of dust, we developed techniques to harvest and separate mycelium-substrate matrices from spores of fungi. Conventional quantitative chromatographic analyses of separated materials indicated that aflatoxin from Aspergillus parasiticus, norsolorinic acid from a mutant of A. parasiticus, and secalonic acid D from Penicillium oxalicum were concentrated in the mycelium-substrate matrices and not in the spores. In contrast, spores of Aspergillus niger and Aspergillus fumigatus contained significant concentrations of aurasperone C and fumigaclavine C, respectively; only negligible amounts of the toxins were detected in the mycelium-substrate matrices of these two fungi. PMID:3709472

Heavy Metal Concentrations in Ceiling Fan Dusts Sampled at Schools Around Serdang Area, Selangor

International Nuclear Information System (INIS)

Yap, C.K.; Krishnan, T.; Chew, W.

2011-01-01

In this study, ceiling fan dust samples were collected from three schools in the district of Serdang Selangor, Malaysia. The sampled dust were analysed for the concentrations of Cd, Cu, Fe, Ni, Pb and Zn. The heavy metal ranges found in all the schools were 2.96-7.74 μg/ g dry weight for Cd, 75-442 μg/ g dry weight for Cu, 3445-3852 μg/ g dry weight for Fe, 24-66 μg/ g dry weight for Ni, 140-734 μg/ g dry weight for Pb and 439-880 μg/ g dry weight for Zn. SMK Seri Serdang School was found to have elevated concentrations of Cd, Cu, Ni, Pb, and Zn which indicated the anthropogenic sources of the study sites. In comparison to other reported studies in the literature, the maximum levels of Cd, Cu, Ni, and Pb were comparable or higher to those cities reported. Therefore, more monitoring studies should be conducted in future since dusts could be related to human health hazards and the dusts can be used as a potential monitoring tool for heavy metal pollution in the atmosphere. (author)

Dust radiative forcing in snow of the Upper Colorado River Basin: 1. A 6 year record of energy balance, radiation, and dust concentrations

Science.gov (United States)

Painter, Thomas H.; Skiles, S. Mckenzie; Deems, Jeffrey S.; Bryant, Ann C.; Landry, Christopher C.

2012-07-01

Dust in snow accelerates snowmelt through its direct reduction of snow albedo and its further indirect reduction of albedo by accelerating the growth of snow grains. Since the westward expansion of the United States that began in the mid-19th century, the mountain snow cover of the Colorado River Basin has been subject to five-fold greater dust loading, largely from the Colorado Plateau and Great Basin. Radiative forcing of snowmelt by dust is not captured by conventional micrometeorological measurements, and must be monitored by a more comprehensive suite of radiation instruments. Here we present a 6 year record of energy balance and detailed radiation measurements in the Senator Beck Basin Study Area, San Juan Mountains, Colorado, USA. Data include broadband irradiance, filtered irradiance, broadband reflected flux, filtered reflected flux, broadband and visible albedo, longwave irradiance, wind speed, relative humidity, and air temperatures. The gradient of the snow surface is monitored weekly and used to correct albedo measurements for geometric effects. The snow is sampled weekly for dust concentrations in plots immediately adjacent to each tower over the melt season. Broadband albedo in the last weeks of snow cover ranged from 0.33 to 0.55 across the 6 years and two sites. Total end of year dust concentration in the top 3 cm of the snow column ranged from 0.23 mg g-1 to 4.16 mg g-1. These measurements enable monitoring and modeling of dust and climate-driven snowmelt forcings in the Upper Colorado River Basin.

Variability in the correlation between Asian dust storms and chlorophyll a concentration from the North to Equatorial Pacific.

Directory of Open Access Journals (Sweden)

Sai-Chun Tan

Full Text Available A long-term record of Asian dust storms showed seven high-occurrence-frequency centers in China. The intrusion of Asian dust into the downwind seas, including the China seas, the Sea of Japan, the subarctic North Pacific, the North Pacific subtropical gyre, and the western and eastern Equatorial Pacific, has been shown to add nutrients to ocean ecosystems and enhance their biological activities. To explore the relationship between the transported dust from various sources to the six seas and oceanic biological activities with different nutrient conditions, the correlation between monthly chlorophyll a concentration in each sea and monthly dust storm occurrence frequencies reaching the sea during 1997-2007 was examined in this study. No correlations were observed between dust and chlorophyll a concentration in the 50 m China seas and the North Pacific subtropical gyre, the correlation coefficients were in the range 0.32-0.57. The correlation coefficients for the western and eastern Equatorial Pacific were relatively low (<0.36. These correlation coefficients were further interpreted in terms of the geographical distributions of dust sources, the transport pathways, the dust deposition, the nutrient conditions of oceans, and the probability of dust storms reaching the seas.

Measuring instrument for the determination of dust concentrations. [air filter with. beta. radiometric gage

Energy Technology Data Exchange (ETDEWEB)

Dresia, H; Spohr, F

1975-05-22

The measuring instrument enables a continuous determination of the dust concentration or total dust content in gases on the basis of the radiometric mass determination of dusts. The partial current method is employed, with the gas fetched through a filter cell with a topped intake by a suction pump. A filter band to take up the dust deposit is continuously driven through the filter cell. The filter point and the measuring point with a ..beta..-radionuclide and a detector are both inside the filter cell. The filter cell is sealed all around, at the entrance and exit of the filter band. The band itself acts as a seal. The filter band also has borders strengthened with, e.g., plastic strips which engage the drive. The widths of the slits are adjustable in height.

The effects of a newsletter on bedding control on house dust mite allergen concentrations in childcare centers in Korea

Directory of Open Access Journals (Sweden)

Jeonghoon Kim

2015-08-01

Full Text Available Objectives Bedding in childcare centers (CCCs can hold house dust mite (HDM allergens. This study examined whether HDM allergen levels can be reduced through the distribution of an educational newsletter on bedding control to parents of CCC children in Korea. Methods All 38 CCCs were measured for Der 1 (sum of Der f 1 and Der p 1 concentrations on classroom floors and bedding before the intervention. Educational newsletters on children’s bedding control were sent to 21 CCCs by mail, and teachers were asked to distribute the newsletters to the parents of the children (intervention group. The remaining 17 CCCs were not sent newsletters (control group. The measurement of Der 1 concentrations in 38 CCCs was repeated after the intervention. Dust samples were collected with a vacuum cleaner and analyzed using enzyme-linked immunosorbent assay methods. Results The Der 1 concentrations on the bedding were significantly higher than those on the floors in 38 CCCs at baseline (p<0.05. Although changes of the Der 1 concentrations for the control group (n=17 were not significant, Der 1 concentrations for the intervention group (n=21 decreased significantly from 2077.9 ng/g dust to 963.5 ng/g dust on the floors and from 3683.9 ng/g dust to 610.4 ng/g dust on bedding (p<0.05. Conclusions The distribution of educational newsletters on bedding control to parents may be an effective means of controlling HDMs in CCCs.

Study on the concentration of airbone respirable asbestos fibres in rural areas of the Lublin region in south-east Poland

Directory of Open Access Journals (Sweden)

Agnieszka Buczaj

2014-09-01

Full Text Available Objective. The objective of the study was measurement of the concentrations of airborne asbestos fibres in the rural environment of the Lublin Region in south-east Poland. Methods. Measurements of concentrations of respirable asbestos fibres were carried out in the rural areas of the Lublin Region (Lublin and Włodawa counties for a period of 24 months. The studies were conducted on 3 farms with various technical conditions of asbestos-containing materials: Farm A – good technical condition of asbestos products, Farm B – poor technical condition, and Farm C – with no asbestos containing products and no such products in its direct vicinity (up to 500 m. On the selected farms, 3 samples on each were simultaneously collected at 3 measuring sites. During the period 2009–2011, a total number of 216 samples were collected on all farms. Sampling was performed using JSH 16,000 stationary aspirators, with air flow velocity of 16 l/min. and sampling time 60–80 minutes. The number of fibres on filters was determined using an optical phase contrast microscope. Results. The study showed that the mean concentration of respirable asbestos fibres on the farms examined was 296 fibres•m [sup]-3[/sup]. The highest concentrations were noted on Farm B was 529 fibres•m [sup]-3[/sup], on average; on farm A the mean concentration of respirable fibres was 328 fibres•m [sup]-3[/sup] , whereas the lowest mean concentration of airborne respirable asbestos fibres was noted on farm C, where there were no asbestos products (30 fibres•m [sup]-3[/sup] .

African dust outbreaks over the Mediterranean Basin during 2001-2011: concentrations, phenomenology and trends

Science.gov (United States)

Pey, Jorge; Querol, Xavier; Alastuey, Andres; Forastiere, Franceso; Stafoggia, Massimo

2013-04-01

Concentrations, phenomenology and trends of African dust outbreaks over the whole Mediterranean Basin werestudied on an 11-year period (2001-2011). This work has been performed in the context of the MED-PARTICLES (LIFE programme, EU) project, devoted to quantify short-term health effects of particulate matter over the Mediterranean region by distinguishing different particle sizes, chemical components and sources, with emphasis in the effects of African dust. In order to evaluate conduct this investigation, PM10 data from 19 regional and suburban background sites West to East in the Mediterranean area were compiled. After identifying the daily occurrence of African dust outbreaks, a methodology for estimating natural dust contributions on daily PM10 concentrations was applied. Our findings point out that African dust outbreaks are sensibly more frequent in southern sitesacross the Mediterranean, from 30 to 37 % of the annual days, whereas they occur less than 20% of the annual days in northern sites. The central Mediterranean emerges as a transitional area, with slightly higher frequency of dust episodes in its lower extreme when compared to similar latitudinal positions in western and eastern sides of the Basin. A decreasing south to north gradient of African dust contribution to PM10, driven by the latitudinal position of the monitoring sites at least 25°E westwards across the Basin,is patent across the Mediterranean. From 25°E eastwards, higher annual dust contributions are encountered due to the elevated annual occurrence of severe episodesof dust but also because of inputs from Middle Eastern deserts. Concerning seasonality patterns and intensity characteristics, a clear summer prevalence is observed in the western part, with low occurrence of severe episodes (daily dust averages over 100 µg m-3 in PM10); no seasonal trend is detected in the central region, with moderate-intensity episodes; and significantly higher contributions are common in autumn

Physico-chemical characterization of grain dust in storage air of Bangalore.

Science.gov (United States)

Mukherjee, A K; Nag, D P; Kakde, Y; Babu, K R; Prdkash, M N; Rao, S R

1998-06-01

An Anderson personal cascade impactor was used to study the particle mass size distribution in the storage air of two major grain storage centers in Bangalore. Dust levels in storage air as well as the personal exposures of workers were determined along with a detailed study on the particle size distribution. Protein and carbohydrate content of the dust were also determined respectively in the phosphate buffer saline (PBS) and water extracts by using the standard analytical techniques. Personal exposures in both of the grain storage centers have been found to be much above the limit prescribed by ACGIH (1995-96). But the results of particle size analysis showed a higher particle mass distribution in the non-respirable size range. The mass median diameters (MMD) of the storage air particulate of both the centers were found to be beyond the respirable range. Presence of protein and carbohydrate in the storage air dust is indicative of the existence of glyco-proteins, mostly of membrane origin.

41 CFR 50-204.50 - Gases, vapors, fumes, dusts, and mists.

Science.gov (United States)

2010-07-01

... Soapstone 20 Talc 20 Portland cement 50 Graphite (natural) 15 Coat dust (respirable fraction less than 5% Si...-selector with the following characteristics: Aerodynamic diameter (unit density sphere) Percent passing...

Risk of Adverse Health and Performance Effects of Celestial Dust Exposure

Science.gov (United States)

Scully, Robert R.; Meyers, Valerie E.

2015-01-01

Crew members can be directly exposed to celestial dust in several ways. After crew members perform extravehicular activities (EVAs), they may introduce into the habitat dust that will have collected on spacesuits and boots. Cleaning of the suits between EVAs and changing of the Environmental Control Life Support System filters are other operations that could result in direct exposure to celestial dusts. In addition, if the spacesuits used in exploration missions abrade the skin, as current EVA suits have, then contact with these wounds would provide a source of exposure. Further, if celestial dusts gain access to a suit's interior, as was the case during the Apollo missions, the dust could serve as an additional source of abrasions or enhance suit-induced injuries. When a crew leaves the surface of a celestial body and returns to microgravity, the dust that is introduced into the return vehicle will "float," thus increasing the opportunity for ocular and respiratory injury. Because the features of the respirable fraction of lunar dusts indicate they could be toxic to humans, NASA conducted several studies utilizing lunar dust simulants and authentic lunar dust to determine the unique properties of lunar dust that affect physiology, assess the dermal and ocular irritancy of the dust, and establish a permissible exposure limit for episodic exposure to airborne lunar dust during missions that would involve no more than 6 months stay on the lunar surface. Studies, with authentic lunar soils from both highland (Apollo 16) and mare (Apollo17) regions demonstrated that the lunar soil is highly abrasive to a high fidelity model of human skin. Studies of lunar dust returned during the Apollo 14 mission from an area of the moon in which the soils were comprised of mineral constituents from both major geological regions (highlands and mares regions) demonstrated only minimal ocular irritancy, and pulmonary toxicity that was less than the highly toxic terrestrial crystalline

Radioactive dust concentration around the Ranger uranium mine

International Nuclear Information System (INIS)

Kavasnicka, Jiri.

1988-07-01

Environmental dust sampling and wind direction/velocity monitory were carried out between July and November 1987 at five points around the Ranger Uranium Mines project near Jabiru, Northern Territory. The measured radioactive dust alpha activities in the air were used to calculate the radioactive dust source-term and develop a site-specific air dispersion model which takes the depletion of the dust plume into account. The above model was used to estimate the effective committed dose equivalent as 15 μSv/year to children in Jabiru East. This corresponds to an increase of 2.6 x 10 -4 Bq. m -3 in the annual average dust alpha activity above the natural background. The dose to the children in Jabiru is about 5 μSv/year, so that the critical group of the public is in Jabiru East. 12 refs., 11 tabs., 2 maps

Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

Science.gov (United States)

Soler-Crespo, R. A.; Monje, O. A.

2010-01-01

Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

Canadian House Dust Study: Population-based concentrations, loads and loading rates of arsenic, cadmium, chromium, copper, nickel, lead, and zinc inside urban homes

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Pat E. [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Levesque, Christine [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Chénier, Marc; Gardner, H. David [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Jones-Otazo, Heather [Regions and Programs Branch, Health Canada, 180 Queen Street West, Toronto, ON, Canada M5V 3L7 (Canada); Petrovic, Sanya [Contaminated Sites Division, Healthy Environments and Consumer Safety Branch, Health Canada, 269 Laurier Ave West, Ottawa, ON, Canada K1A 0K9 (Canada)

2013-01-15

The Canadian House Dust Study was designed to obtain nationally representative urban house dust metal concentrations (μg g{sup −1}) and metal loadings (μg m{sup −2}) for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Consistent sampling of active dust of known age and provenance (area sampled) also permitted the calculation of indoor loading rates (mg m{sup −2} day{sup −1} for dust and μg m{sup −2} day{sup −1} for metals) for the winter season (from 2007 to 2010) when houses are most tightly sealed. Geomean/median indoor dust loading rates in homes located more than 2 km away from industry of any kind (9.6/9.1 mg m{sup −2} day{sup −1}; n = 580) were significantly lower (p < .001) than geomean (median) dust loading rates in homes located within 2 km of industry (13.5/13.4 mg m{sup −2} day{sup −1}; n = 421). Proximity to industry was characterized by higher indoor metal loading rates (p < .003), but no difference in dust metal concentrations (.29 ≥ p ≤ .97). Comparisons of non-smokers' and smokers' homes in non-industrial zones showed higher metal loading rates (.005 ≥ p ≤ .038) in smokers' homes, but no difference in dust metal concentrations (.15 ≥ p ≤ .97). Relationships between house age and dust metal concentrations were significant for Pb, Cd and Zn (p < .001) but not for the other four metals (.14 ≥ p ≤ .87). All seven metals, however, displayed a significant increase in metal loading rates with house age (p < .001) due to the influence of higher dust loading rates in older homes (p < .001). Relationships between three measures of metals in house dust – concentration, load, and loading rate – in the context of house age, smoking behavior and urban setting consistently show that concentration data is a useful indicator of the presence of metal sources in the home, whereas dust mass is the overriding influence on metal loadings and loading rates

Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure.

Science.gov (United States)

Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S Katharine

2015-03-01

This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57-410) in gasoline buses and 3.97 ± 1.81 (range: 2.01-9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of radon-daughter exposure rate and uranium ore dust concentration on occurrence of lung tumors

International Nuclear Information System (INIS)

Cross, F.T.; Palmer, R.F.; Busch, R.H.

1980-01-01

Groups of male SPF Wistar rats were exposed concurrently to several levels of radon daughters and uranium ore dust to study the effect of these variables on pulmonary disease states. Clinical pathology data at 1 yr postexposure indicate no significant differences among exposed animals when compared with controls. Preliminary histopathologic data suggest a trend toward increasing lung tumor risk as the exposure rate is decreased (constant total dose), but the differences are not statistically significant at the 0.05 level. A similar trend occurs with decrease in ore dust concentration (except for the 2560-WLM exposure group), but these differences are also not significant at the 0.05 level. The tumor risk is significantly (0.05 level) increased as the exposure level increases from approximately 320 and 640 WLM to 2560 WLM at the high ore dust concentration

The spatial concentration of dust emissions measured by using 3D scanning lidar in the open storage yards of steel-making company

Science.gov (United States)

Chiang, Chih-Wei; Chiang, Hong-Wei; Chou, Huann-Ming; Sun, Shu-Huang; Lee, Jiann-Shen

2017-06-01

The wind-blown dust emissions frequently occur in the open storage yards of steel-making companies. Tracking the dust source and monitoring their dispersion are rather difficult. This type of open-air storage yards poses many environmental hazards. The 3-D scanning lidar system is effective in environmental monitoring (e.g., dust) with high temporal and spatial resolution, which is lacking in traditional ground-based measurement. The objective of this paper is to make an attempt for the flux estimation of dust concentration by using lidar system. Further, we investigate the dynamical process of dust and their relationship with local air quality monitoring data. The results show that the material storage erosion by wind ( 3.6 m/s) could cause dust to elevate up to 20m height above the material storage, and produces the flux of dust around 674 mg/s. The flux of dust is proportional to the dust mass concentration (PM10) measured by commercial ambient particular monitors.

The role of dust storms in total atmospheric particle concentrations at two sites in the western U.S.

Science.gov (United States)

Neff, Jason C.; Reynolds, Richard L.; Munson, Seth M.; Fernandez, Daniel; Belnap, Jayne

2013-01-01

Mineral aerosols are produced during the erosion of soils by wind and are a common source of particles (dust) in arid and semiarid regions. The size of these particles varies widely from less than 2 µm to larger particles that can exceed 50 µm in diameter. In this study, we present two continuous records of total suspended particle (TSP) concentrations at sites in Mesa Verde and Canyonlands National Parks in Colorado and Utah, USA, respectively, and compare those values to measurements of fine and coarse particle concentrations made from nearby samplers. Average annual concentrations of TSP at Mesa Verde were 90 µg m−3 in 2011 and at Canyonlands were 171 µg m−3 in 2009, 113 µg m−3 in 2010, and 134 µg m−3 in 2011. In comparison, annual concentrations of fine (diameter of 2.5 µm and below) and coarse (2.5–10 µm diameter) particles at these sites were below 10 µg m−3 in all years. The high concentrations of TSP appear to be the result of regional dust storms with elevated concentrations of particles greater than 10 µm in diameter. These conditions regularly occur from spring through fall with 2 week mean TSP periodically in excess of 200 µg m−3. Measurement of particles on filters indicates that the median particle size varies between approximately 10 µm in winter and 40 µm during the spring. These persistently elevated concentrations of large particles indicate that regional dust emission as dust storms and events are important determinants of air quality in this region.

Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

Science.gov (United States)

García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

2017-11-01

Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth integrated community respiration was

Direct-on-Filter α-Quartz Estimation in Respirable Coal Mine Dust Using Transmission Fourier Transform Infrared Spectrometry and Partial Least Squares Regression.

Science.gov (United States)

Miller, Arthur L; Weakley, Andrew Todd; Griffiths, Peter R; Cauda, Emanuele G; Bayman, Sean

2017-05-01

In order to help reduce silicosis in miners, the National Institute for Occupational Health and Safety (NIOSH) is developing field-portable methods for measuring airborne respirable crystalline silica (RCS), specifically the polymorph α-quartz, in mine dusts. In this study we demonstrate the feasibility of end-of-shift measurement of α-quartz using a direct-on-filter (DoF) method to analyze coal mine dust samples deposited onto polyvinyl chloride filters. The DoF method is potentially amenable for on-site analyses, but deviates from the current regulatory determination of RCS for coal mines by eliminating two sample preparation steps: ashing the sampling filter and redepositing the ash prior to quantification by Fourier transform infrared (FT-IR) spectrometry. In this study, the FT-IR spectra of 66 coal dust samples from active mines were used, and the RCS was quantified by using: (1) an ordinary least squares (OLS) calibration approach that utilizes standard silica material as done in the Mine Safety and Health Administration's P7 method; and (2) a partial least squares (PLS) regression approach. Both were capable of accounting for kaolinite, which can confound the IR analysis of silica. The OLS method utilized analytical standards for silica calibration and kaolin correction, resulting in a good linear correlation with P7 results and minimal bias but with the accuracy limited by the presence of kaolinite. The PLS approach also produced predictions well-correlated to the P7 method, as well as better accuracy in RCS prediction, and no bias due to variable kaolinite mass. Besides decreased sensitivity to mineral or substrate confounders, PLS has the advantage that the analyst is not required to correct for the presence of kaolinite or background interferences related to the substrate, making the method potentially viable for automated RCS prediction in the field. This study demonstrated the efficacy of FT-IR transmission spectrometry for silica determination in

Effects of elevated CO2 concentrations on photosynthesis, dark res-piration and RuBPcase activity of three species seedlings in Changbai Mountain

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

Two-year-old seedlings of Pinus koraiensis, Pinus sylvestriformis and Fraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L-1, 500 μL·L-1) and ambient CO2 concentrations (350 μL·L-1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species except P. sylvestriformis grown under 500 μL·L-1 CO2 concentration. The dark respiration rates of P. koraiensis and P. sylvestriformis increased under concentration of 700 μL·L-1 CO2, but that of F. mandshurica decreased under both concentrations 700 μL·L-1 and 500 μL·L-1 CO2. The seedlings of F. mandshurica decreased in chlorophyll contents at elevat-ed CO2 concentrations.

Change of exposure response over time and long-term risk of silicosis among a cohort of Chinese pottery workers.

Science.gov (United States)

Sun, Yi; Bochmann, Frank; Morfeld, Peter; Ulm, Kurt; Liu, Yuewei; Wang, Heijiao; Yang, Lei; Chen, Weihong

2011-07-01

An analysis was conducted on a cohort of Chinese pottery workers to estimate the exposure-response relationship between respirable crystalline silica dust exposure and the incidence of radiographically diagnosed silicosis, and to estimate the long-term risk of developing silicosis until the age of 65. The cohort comprised 3,250 employees with a median follow-up duration of around 37 years. Incident cases of silicosis were identified via silicosis registries (Chinese X-ray stage I, similar to International Labor Organisation classification scheme profusion category 1/1). Individual exposure to respirable crystalline silica dust was estimated based on over 100,000 historical dust measurements. The association between dust exposure, incidence and long-time risk of silicosis was quantified by Poisson regression analysis adjusted for age and smoking. The risk of silicosis depended not only on the cumulative respirable crystalline silica dust exposures, but also on the time-dependent respirable crystalline silica dust exposure pattern (long-term average concentration, highest annual concentration ever experienced and time since first exposure). A long-term "excess" risk of silicosis of approximately 1.5/1,000 was estimated among workers with all annual respirable crystalline silica dust concentration estimates less than 0.1 mg/m(3), using the German measurement strategy. This study indicates the importance of proper consideration of exposure information in risk quantification in epidemiological studies.

Change of Exposure Response over Time and Long-Term Risk of Silicosis among a Cohort of Chinese Pottery Workers

Directory of Open Access Journals (Sweden)

Yuewei Liu

2011-07-01

Full Text Available An analysis was conducted on a cohort of Chinese pottery workers to estimate the exposure-response relationship between respirable crystalline silica dust exposure and the incidence of radiographically diagnosed silicosis, and to estimate the long-term risk of developing silicosis until the age of 65. The cohort comprised 3,250 employees with a median follow-up duration of around 37 years. Incident cases of silicosis were identified via silicosis registries (Chinese X-ray stage I, similar to International Labor Organisation classification scheme profusion category 1/1. Individual exposure to respirable crystalline silica dust was estimated based on over 100,000 historical dust measurements. The association between dust exposure, incidence and long-time risk of silicosis was quantified by Poisson regression analysis adjusted for age and smoking. The risk of silicosis depended not only on the cumulative respirable crystalline silica dust exposures, but also on the time-dependent respirable crystalline silica dust exposure pattern (long-term average concentration, highest annual concentration ever experienced and time since first exposure. A long-term “excess” risk of silicosis of approximately 1.5/1,000 was estimated among workers with all annual respirable crystalline silica dust concentration estimates less than 0.1 mg/m3, using the German measurement strategy. This study indicates the importance of proper consideration of exposure information in risk quantification in epidemiological studies.

30 CFR 90.201 - Sampling; general requirements.

Science.gov (United States)

2010-07-01

... operational during the entire shift or for 8 hours, whichever time is less. (c) Upon request from the District... respirable dust samples of the concentration of respirable dust in the active workings of the mine as... of the normal working position; or (3) At a location that represents the maximum concentration of...

Respiratory health effects of occupational exposure to charcoal dust in Namibia

Science.gov (United States)

Kgabi, Nnenesi

2016-01-01

Background Charcoal processing activities can increase the risk of adverse respiratory outcomes. Objective To determine dose–response relationships between occupational exposure to charcoal dust, respiratory symptoms and lung function among charcoal-processing workers in Namibia. Methods A cross-sectional study was conducted with 307 workers from charcoal factories in Namibia. All respondents completed interviewer-administered questionnaires. Spirometry was performed, ambient and respirable dust levels were assessed in different work sections. Multiple logistic regression analysis estimated the overall effect of charcoal dust exposure on respiratory outcomes, while linear regression estimated the exposure-related effect on lung function. Workers were stratified according to cumulative dust exposure category. Results Exposure to respirable charcoal dust levels was above occupational exposure limits in most sectors, with packing and weighing having the highest dust exposure levels (median 27.7 mg/m3, range: 0.2–33.0 for the 8-h time-weighted average). The high cumulative dust exposure category was significantly associated with usual cough (OR: 2.1; 95% CI: 1.1–4.0), usual phlegm (OR: 2.1; 95% CI: 1.1–4.1), episodes of phlegm and cough (OR: 2.8; 95% CI: 1.1–6.1), and shortness of breath. A non-statistically significant lower adjusted mean-predicted % FEV1 was observed (98.1% for male and 95.5% for female) among workers with greater exposure. Conclusions Charcoal dust levels exceeded the US OSHA recommended limit of 3.5 mg/m3 for carbon-black-containing material and study participants presented with exposure-related adverse respiratory outcomes in a dose–response manner. Our findings suggest that the Namibian Ministry of Labour introduce stronger enforcement strategies of existing national health and safety regulations within the industry. PMID:27687528

Concentrations of polycyclic aromatic hydrocarbons in resuspendable fraction of settled bus dust and its implications for human exposure

International Nuclear Information System (INIS)

Gao, Peng; Liu, Sa; Feng, Yujie; Lin, Nan; Lu, Binyu; Zhang, Zhaohan; Cui, Fuyi; Xing, Baoshan; Hammond, S. Katharine

2015-01-01

This preliminary study measured Polycyclic Aromatic Hydrocarbons (PAHs) concentrations in the resuspendable fraction of settled dust on 39 bus lines, to evaluate the impact of engine type (gasoline and compressed natural gas) on exposure for commuters and drivers. Benzo(b)fluoranthene(BbF) was the predominant PAH in resuspendable fraction of settled bus dust. The concentration of total PAHs was 92.90 ± 116.00 μg/g (range: 0.57–410) in gasoline buses and 3.97 ± 1.81 (range: 2.01–9.47) in compressed natural gas (CNG) buses. Based on Benzo[a]pyrene (BaP) equivalent concentrations for the sum of 16 PAHs, the average daily dose (ADD) via dust ingestion and dermal contact was calculated. The ADD of PAHs was higher for commuters and drivers in gasoline-powered buses than in buses using CNG buses. For both short and long duration journeys, young commuters were exposed to higher levels of PAHs via dust ingestion and dermal contact than adult commuters. - Highlights: • Resuspendable fraction of settled dust from microenvironment of buses in Harbin monitored for PAHs exposure assessment. • Higher levels of PAHs pollutants at gasoline-powered buses than at compressed natural gas-powered buses. • Non-occupational and occupational exposures in the microenvironment of buses are assessed. - Occupational and non-occupational exposure to PAHs from the microenvironment of bus

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

Energy Technology Data Exchange (ETDEWEB)

Gonzales, Patricia; Felix, Omar [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Alexander, Caitlin; Lutz, Eric [Division of Community, Environment, and Policy, Mel and Enid Zuckerman College of Public Health, University of Arizona, 1656 E. Mabel St., Tucson, AZ 85724 (United States); Ela, Wendell [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States); Eduardo Sáez, A., E-mail: esaez@arizona.edu [Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721 (United States)

2014-09-15

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure.

Laboratory dust generation and size-dependent characterization of metal and metalloid-contaminated mine tailings deposits

International Nuclear Information System (INIS)

Gonzales, Patricia; Felix, Omar; Alexander, Caitlin; Lutz, Eric; Ela, Wendell; Eduardo Sáez, A.

2014-01-01

Highlights: • A laboratory dust fractionator was developed for the production of respirable dust. • The size-dependent distribution of arsenic and lead in mine tailings dust is reported. • Metal and metalloid contaminants are enriched in particles smaller than 10 μm. • Lead isotope signatures show spread of mine tailings particles onto surrounding soils. - Abstract: The particle size distribution of mine tailings material has a major impact on the atmospheric transport of metal and metalloid contaminants by dust. Implications to human health should be assessed through a holistic size-resolved characterization involving multidisciplinary research, which requires large uniform samples of dust that are difficult to collect using conventional atmospheric sampling instruments. To address this limitation, we designed a laboratory dust generation and fractionation system capable of producing several grams of dust from bulk materials. The equipment was utilized in the characterization of tailings deposits from the arsenic and lead-contaminated Iron King Superfund site in Dewey-Humboldt, Arizona. Results show that metal and metalloid contaminants are more concentrated in particles of <10 μm aerodynamic diameter, which are likely to affect surrounding communities and ecosystems. In addition, we traced the transport of contaminated particles from the tailings to surrounding soils by identifying Pb and Sr isotopic signatures in soil samples. The equipment and methods developed for this assessment ensure uniform samples for further multidisciplinary studies, thus providing a tool for comprehensive representation of emission sources and associated risks of exposure

Mortality over an extended follow-up period in coal workers exposed to respirable dust and quartz

Energy Technology Data Exchange (ETDEWEB)

Miller, B.G.; MacCalman, L.; Hutchison, P.A.

2009-10-15

In the 1950s the Pneumoconiosis Field Research (PFR) programme was set up to study the health of British coalworkers. Studies included regular health surveys, an intensive characterisation of workers' individual exposures, and entry to a cohort followed up to the present for cause-specific mortality. This study reports on analyses of cause-specific mortality in a cohort of almost 18,000 men from 10 collieries. External analyses used standardised mortality ratios, comparing observed mortality with reference rates from the regions in which the pits were situated. Causes investigated include lung and stomach cancers, nonmalignant respiratory diseases, and cardiovascular endpoints. Internal analyses used Cox regression models with time-dependent exposures adjusting for the confounding effects of age, smoking, cohort entry date and regional differences in population mortality rates. Several causes showed evidence of a healthy worker effect early in the follow-up, with a deficit in the SMR diminishing over time. For most of the causes there was a significant excess in the latter part of follow-up. Internal analyses found evidence of an association between increased risks of lung cancer and increased quartz exposure, particularly at a lag of 15 years. Risks of mortality from non-malignant respiratory disease, and specifically chronic obstructive pulmonary disease and pneumoconiosis, showed increases with increased exposure to respirable dust. 60 refs.

Mortality from non-malignant respiratory diseases among people with silicosis in Hong Kong: exposure-response analyses for exposure to silica dust.

Science.gov (United States)

Tse, L A; Yu, I T S; Leung, C C; Tam, W; Wong, T W

2007-02-01

To examine the exposure-response relationships between various indices of exposure to silica dust and the mortality from non-malignant respiratory diseases (NMRDs) or chronic obstructive pulmonary diseases (COPDs) among a cohort of workers with silicosis in Hong Kong. The concentrations of respirable silica dust were assigned to each industry and job task according to historical industrial hygiene measurements documented previously in Hong Kong. Exposure indices included cumulative dust exposure (CDE) and mean dust concentration (MDC). Penalised smoothing spline models were used as a preliminary step to detect outliers and guide further analyses. Multiple Cox's proportional hazard models were used to estimate the dust effects on the risk of mortality from NMRDs or COPDs after truncating the highest exposures. 371 of the 853 (43.49%) deaths occurring among 2789 workers with silicosis during 1981-99 were from NMRDs, and 101 (27.22%) NMRDs were COPDs. Multiple Cox's proportional hazard models showed that CDE (p = 0.009) and MDC (pcaisson workers and among those ever employed in other occupations with high exposure to silica dust. No exposure-response relationship was observed for surface construction workers with low exposures. A clear upward trend for both NMRDs and COPDs mortality was found with increasing severity of radiological silicosis. This study documented an exposure-response relationship between exposure to silica dust and the risk of death from NMRDs or COPDs among workers with silicosis, except for surface construction workers with low exposures. The risk of mortality from NMRDs increased significantly with the progression of International Labor Organization categories, independent of dust effects.

Cow allergen (Bos d2) and endotoxin concentrations are higher in the settled dust of homes proximate to industrial-scale dairy operations.

Science.gov (United States)

Williams, D' Ann L; McCormack, Meredith C; Matsui, Elizabeth C; Diette, Gregory B; McKenzie, Shawn E; Geyh, Alison S; Breysse, Patrick N

2016-01-01

Airborne contaminants produced by industrial agricultural facilities contain chemical and biological compounds that can impact the health of residents living in close proximity. Settled dust can be a reservoir for these contaminants and can influence long-term exposures. In this study, we sampled the indoor- and outdoor-settled dust from 40 homes that varied in proximity to industrial-scale dairies (ISD; industrial-scale dairy, a term used in this paper to describe a large dairy farm and adjacent waste sprayfields, concentrated animal feeding operation or animal feeding operation, that uses industrial processes) in the Yakima Valley, Washington. We analyzed settled dust samples for cow allergen (Bos d2, a cow allergen associated with dander, hair, sweat and urine, it is a member of the lipocalin family of allergens associated with mammals), mouse allergen (Mus m1; major mouse allergen, a mouse urinary allergen, in the lipocalin family), dust mite allergens (Der p1 (Dermatophagoides pteronissinus 1) and Der f1 (Dermatophagoides farinae 1)), and endotoxin (a component of the cell walls of gram negative bacteria, lipopolysaccharide, which can be found in air and dust and can produce a strong inflammatory response). A concentration gradient was observed for Bos d2 and endotoxin measured in outdoor-settled dust samples based on proximity to ISD. Indoor-settled dust concentrations of Bos d2 and endotoxin were also highest in proximal homes. While the associated health effects of exposure to cow allergen in settled dust is unknown, endotoxin at concentrations observed in these proximal homes (100 EU/mg) has been associated with increased negative respiratory health effects. These findings document that biological contaminants emitted from ISDs are elevated in indoor- and outdoor-settled dust samples at homes close to these facilities and extend to as much as three miles (4.8 km) away.

Plant species richness regulates soil respiration through changes in productivity.

Science.gov (United States)

Dias, André Tavares Corrêa; van Ruijven, Jasper; Berendse, Frank

2010-07-01

Soil respiration is an important pathway of the C cycle. However, it is still poorly understood how changes in plant community diversity can affect this ecosystem process. Here we used a long-term experiment consisting of a gradient of grassland plant species richness to test for effects of diversity on soil respiration. We hypothesized that plant diversity could affect soil respiration in two ways. On the one hand, more diverse plant communities have been shown to promote plant productivity, which could increase soil respiration. On the other hand, the nutrient concentration in the biomass produced has been shown to decrease with diversity, which could counteract the production-induced increase in soil respiration. Our results clearly show that soil respiration increased with species richness. Detailed analysis revealed that this effect was not due to differences in species composition. In general, soil respiration in mixtures was higher than would be expected from the monocultures. Path analysis revealed that species richness predominantly regulates soil respiration through changes in productivity. No evidence supporting the hypothesized negative effect of lower N concentration on soil respiration was found. We conclude that shifts in productivity are the main mechanism by which changes in plant diversity may affect soil respiration.

Silica exposure to excavation workers during the excavation of a low level radiological waste pit and tritium disposal shafts

International Nuclear Information System (INIS)

Wilson, K.M.

1995-01-01

This study evaluated the task-length average (TLA) respirable dust and respirable silica airborne concentrations to which construction workers excavating volcanic tuff at Los Alamos National Laboratory (LANL) were exposed. These workers were excavating a low level radiological waste disposal pit of final dimensions 720 feet long, 132 feet wide and 60 feet deep. The objectives of this study were as follows: (1) evaluate exposures; (2) determine if the type of machinery used affects the respirable dust concentration in the breathing zone of the worker; (3) evaluate the efficacy of wetting the pit to reduce the respirable dust exposure; and (4) determine if exposure increases with increasing depth of pit due to the walls of the pit blocking the cross wind ventilation

Dust exposure, eye redness, eye cytology and mucous membrane irritation in a tobacco industry

DEFF Research Database (Denmark)

Kjærgaard, Søren K.; Pedersen, O.F.

1989-01-01

In a study of 75 workers employed in a tobacco factory producing cheroots we measured cellular contents of tear fluid, redness of eyes, discomfort, total (0–5.7 mg/m3) and respirable dust in the breathing zone and total ambient dust by stationary sampling (0.08–1.0 mg/m3). A matched group of 50 o...

Experimental human exposure to inhaled grain dust and ammonia: towards a model of concentrated animal feeding operations.

Science.gov (United States)

Sigurdarson, Sigurdur T; O'Shaughnessy, Patrick T; Watt, Janet A; Kline, Joel N

2004-10-01

Ammonia and endotoxin-rich dust are present in high concentrations in swine confinement facilities; exposure to this environment is linked to workers' respiratory problems. We hypothesized that experimental exposure to ammonia and dust would impair pulmonary function, and that these exposures would be synergistic. We exposed six normal subjects and eight subjects with mild asthma to ammonia (16-25 ppm) and/or endotoxin-rich grain dust (4 mg/m3). Pulmonary function and exhaled NOx were measured before and after exposure. There was no significant change in pulmonary function in the normal subjects following any of the exposure conditions. Among asthmatics, a significant transient decrease in FEV1 was induced by grain dust, but was not altered by ammonia; increased bronchial hyperreactivity was also noted in this group. In a vulnerable population, exposure to grain dust results in transient airflow obstruction. Short-term exposure to ammonia does not increase this response.

Measurement and Modeling of Respiration Rate of Tomato (Cultivar Roma) for Modified Atmosphere Storage.

Science.gov (United States)

Kandasamy, Palani; Moitra, Ranabir; Mukherjee, Souti

2015-01-01

Experiments were conducted to determine the respiration rate of tomato at 10, 20 and 30 °C using closed respiration system. Oxygen depletion and carbon dioxide accumulation in the system containing tomato was monitored. Respiration rate was found to decrease with increasing CO2 and decreasing O2 concentration. Michaelis-Menten type model based on enzyme kinetics was evaluated using experimental data generated for predicting the respiration rate. The model parameters that obtained from the respiration rate at different O2 and CO2 concentration levels were used to fit the model against the storage temperatures. The fitting was fair (R2 = 0.923 to 0.970) when the respiration rate was expressed as O2 concentation. Since inhibition constant for CO2 concentration tended towards negetive, the model was modified as a function of O2 concentration only. The modified model was fitted to the experimental data and showed good agreement (R2 = 0.998) with experimentally estimated respiration rate.

Does an elevated CO₂ concentration decrease dark respiration in trees? Final technical report

Energy Technology Data Exchange (ETDEWEB)

Long, Stephen [Univ. of Illinois, Urbana-Champaign, IL (United States)

2003-12-31

Averaged across many previous investigations, doubling the CO₂ concentration ([CO₂]) has frequently been reported to cause an instantaneous reduction of leaf dark respiration measured as CO₂ efflux. No known mechanism accounts for this effect. While four recent studies have shown that the measurement of respiratory CO₂ efflux is prone to experimental artifacts that could account for the reported response, papers published since the start of the current research continue to report an instantaneous depression of respiratory CO₂ efflux by elevation of [CO₂]. Here, these artifacts are avoided by use of a high-resolution dual channel oxygen analyzer within an open gas exchange system to measure respiratory 02 uptake in normal air. Leaf 02 uptake was determined in response to instantaneous elevation of [CO₂] in nine contrasting species and to long-term elevation in seven species from four of the DOE-sponsored long-term elevated [CO₂] field experiments. Over one thousand separate measurements of respiration failed to reveal any decrease in respiratory 02 uptake with an instantaneous increase in [CO₂]. Respiration was found insensitive not only to doubling [CO₂], but also to a five-fold increase and to decrease to zero.

Effect of fluorine and of beta-indolacetic acid on the respiration of root tissue

Energy Technology Data Exchange (ETDEWEB)

Pilet, P E

1964-01-01

The auxin, beta-indolacetic acid, (BIAA) inhibited the elongation of Lens culinaris roots at all concentrations. At high concentrations fluoride had an inhibitor effect, but it had a stimulatory effect on root growth at low concentrations. BIAA mildly stimulated respiration at low concentrations and inhibited oxygen absorption at high concentrations. At concentrations stimulating respiration fluoride was found to reduce these stimulating effects caused by BIAA. Therefore, fluoride and BIAA acted as antagonists in their effect on respiration.

Lunar Airborne Dust Toxicity Hazard Assessments (Invited)

Science.gov (United States)

Cooper, B. L.; McKay, D. S.; Taylor, L. A.; Wallace, W. T.; James, J.; Riofrio, L.; Gonzalez, C. P.

2009-12-01

The Lunar Airborne Dust Toxicity Assessment Group (LADTAG) is developing data to set the permissible limits for human exposure to lunar dust. This standard will guide the design of airlocks and ports for EVA, as well as the requirements for filtering and monitoring the atmosphere in habitable vehicles, rovers and other modules. LADTAG’s recommendation for permissible exposure limits will be delivered to the Constellation Program in late 2010. The current worst-case exposure limit of 0.05 mg/m3, estimated by LADTAG in 2006, reflects the concern that lunar dust may be as toxic as quartz dust. Freshly-ground quartz is known to be more toxic than un-ground quartz dust. Our research has shown that the surfaces of lunar soil grains can be more readily activated by grinding than quartz. Activation was measured by the amount of free radicals generated—activated simulants generate Reactive Oxygen Species (ROS) i.e., production of hydroxyl free radicals. Of the various influences in the lunar environment, micrometeorite bombardment probably creates the most long-lasting reactivity on the surfaces of grains, although solar wind impingement and short-wavelength UV radiation also contribute. The comminution process creates fractured surfaces with unsatisfied bonds. When these grains are inhaled and carried into the lungs, they will react with lung surfactant and cells, potentially causing tissue damage and disease. Tests on lunar simulants have shown that dissolution and leaching of metals can occur when the grains are exposed to water—the primary component of lung fluid. However, simulants may behave differently than actual lunar soils. Rodent toxicity testing will be done using the respirable fraction of actual lunar soils (particles with physical size of less than 2.5 micrometers). We are currently separating the fine material from the coarser material that comprises >95% of the mass of each soil sample. Dry sieving is not practical in this size range, so a new system

Total and respirable dust exposures among carpenters and demolition workers during indoor work in Denmark

DEFF Research Database (Denmark)

Kirkeskov, Lilli; Hanskov, Dorte Jessing Agerby; Brauer, Charlotte

2016-01-01

BACKGROUND: Within the construction industry the risk of lung disorders depends on the specific professions probably due to variations in the levels of dust exposure, and with dust levels depending on the work task and job function. We do not know the extent of exposure in the different professions...... was 3.90 (95 % confidence interval 1.13-13.5) mg/m(3). Dust exposure varied depending on work task for both professions. The dustiest work occurred during demolition, especially when it was done manually. Only few workers used personal respiratory protection and only while performing the dustiest work...... or the variation between the different work tasks. The purpose of this study was therefore to assess if there were differences in dust exposure between carpenters and demolition workers who were expected to have low and high dust exposure, respectively. METHODS: Through interviews of key persons...

Mortality from non‐malignant respiratory diseases among people with silicosis in Hong Kong: exposure–response analyses for exposure to silica dust

Science.gov (United States)

Tse, L A; Yu, I T S; Leung, C C; Tam, W; Wong, T W

2007-01-01

Objectives To examine the exposure–response relationships between various indices of exposure to silica dust and the mortality from non‐malignant respiratory diseases (NMRDs) or chronic obstructive pulmonary diseases (COPDs) among a cohort of workers with silicosis in Hong Kong. Methods The concentrations of respirable silica dust were assigned to each industry and job task according to historical industrial hygiene measurements documented previously in Hong Kong. Exposure indices included cumulative dust exposure (CDE) and mean dust concentration (MDC). Penalised smoothing spline models were used as a preliminary step to detect outliers and guide further analyses. Multiple Cox's proportional hazard models were used to estimate the dust effects on the risk of mortality from NMRDs or COPDs after truncating the highest exposures. Results 371 of the 853 (43.49%) deaths occurring among 2789 workers with silicosis during 1981–99 were from NMRDs, and 101 (27.22%) NMRDs were COPDs. Multiple Cox's proportional hazard models showed that CDE (p = 0.009) and MDC (pcaisson workers and among those ever employed in other occupations with high exposure to silica dust. No exposure–response relationship was observed for surface construction workers with low exposures. A clear upward trend for both NMRDs and COPDs mortality was found with increasing severity of radiological silicosis. Conclusion This study documented an exposure–response relationship between exposure to silica dust and the risk of death from NMRDs or COPDs among workers with silicosis, except for surface construction workers with low exposures. The risk of mortality from NMRDs increased significantly with the progression of International Labor Organization categories, independent of dust effects. PMID:16973737

Inhalation Toxicity of Ground Lunar Dust Prepared from Apollo-14 Soil

Science.gov (United States)

James, John T.; Lam, Chiu-wing; Scully, Robert R.; Cooper, Bonnie L.

2011-01-01

Within the decade one or more space-faring nations intend to return humans to the moon for more in depth exploration of the lunar surface and subsurface than was conducted during the Apollo days. The lunar surface is blanketed with fine dust, much of it in the respirable size range (<10 micron). Eventually, there is likely to be a habitable base and rovers available to reach distant targets for sample acquisition. Despite designs that could minimize the entry of dust into habitats and rovers, it is reasonable to expect lunar dust to pollute both as operations progress. Apollo astronauts were exposed briefly to dust at nuisance levels, but stays of up to 6 months on the lunar surface are envisioned. Will repeated episodic exposures to lunar dust present a health hazard to those engaged in lunar exploration? Using rats exposed to lunar dust by nose-only inhalation, we set out to investigate that question.

Correlation between Yellow Dust and Radioactivity

International Nuclear Information System (INIS)

AIZaabia, Mouza A; Kim, Byoung-Jik

2015-01-01

In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, 137 Cs and 7 Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides

The concentration, source and deposition flux of ammonium and nitrate in atmospheric particles during dust events at a coastal site in northern China

Science.gov (United States)

Qi, Jianhua; Liu, Xiaohuan; Yao, Xiaohong; Zhang, Ruifeng; Chen, Xiaojing; Lin, Xuehui; Gao, Huiwang; Liu, Ruhai

2018-01-01

Asian dust has been reported to carry anthropogenic reactive nitrogen during transport from source areas to the oceans. In this study, we attempted to characterize NH4+ and NO3- in atmospheric particles collected at a coastal site in northern China during spring dust events from 2008 to 2011. Based on the mass concentrations of NH4+ and NO3- in each total suspended particle (TSP) sample, the samples can be classified into increasing or decreasing types. In Category 1, the concentrations of NH4+ and NO3- were 20-440 % higher in dust day samples relative to samples collected immediately before or after a dust event. These concentrations decreased by 10-75 % in the dust day samples in Categories 2 and 3. Back trajectory analysis suggested that multiple factors, such as the transport distance prior to the reception site, the mixing layer depth on the transport route and the residence time across highly polluted regions, might affect the concentrations of NH4+ and NO3-. NH4+ in the dust day samples was likely either in the form of ammonium salts existing separately to dust aerosols or as the residual of incomplete reactions between ammonium salts and carbonate salts. NO3- in the dust day samples was attributed to various formation processes during the long-range transport. The positive matrix factorization (PMF) receptor model results showed that the contribution of soil dust increased from 23 to 36 % on dust days, with decreasing contributions from local anthropogenic inputs and associated secondary aerosols. The estimated deposition flux of NNH4++NO3- varied greatly from event to event; e.g., the dry deposition flux of NNH4++NO3- increased by 9-285 % in Category 1 but decreased by 46-73 % in Category 2. In Category 3, the average dry deposition fluxes of particulate nitrate and ammonium decreased by 46 % and increased by 10 %, respectively, leading to 11-48 % decrease in the fluxes of NNH4++NO3-.

Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2.

Science.gov (United States)

Cummings, Beth; Hamilton, Michelle L; Ciaffoni, Luca; Pragnell, Timothy R; Peverall, Rob; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

2011-07-01

The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations.

In vitro release of arachidonic acid and in vivo responses to respirable fractions of cotton dust

International Nuclear Information System (INIS)

Thomson, T.A.; Edwards, J.H.; Al-Zubaidy, T.S.; Brown, R.C.; Poole, A.; Nicholls, P.J.

1986-01-01

It was considered that the fall in lung function seen after exposure to cotton dust may be attributable in part to the activity of arachidonic acid metabolites, such as leucotrienes as well as to the more established release of histamine by cotton dust. However, we found that cotton and barley dusts elicited poor release of arachidonic acid from an established macrophage like cell line compared with that observed with other organic dusts. In the experimental animal, pulmonary cellular responses to both cotton and barley dust were similar to those evoked by moldy hay and pigeon dropping dusts, although after multiple doses a more severe response was seen to cotton and barley. Since both moldy hay and pigeon droppings elicit a greater arachidonic acid release than cotton or barley, a role for arachidonic acid in inducing the cellular response is less likely than other factors. There are limitations to our conclusions using this system, i.e., the arachidonic acid may be released in a nonmetabolized form, although it is noted that the two dusts with the greatest arachidonic acid release produce their clinical responses in humans largely by hypersensitivity mechanisms

CHARACTERIZATION OF THE DUST GENERATED IN THE RECYCLING PROCESS OF THE ELECTRIC ARC FURNACE DUST

Directory of Open Access Journals (Sweden)

Fábio Gonçalves Rizz

2013-10-01

Full Text Available Electric Arc Furnace Dust (EAFD is a solid waste generated by the production of steel through the Electric Arc Furnace. This waste is labeled dangerous, which motivates studies aiming its recycling. Experiments were made to study a pyrometallurgical process for the recycling of the dust, using the insertion of dust briquettes in molten pig iron in three temperatures. In the briquettes, there were made additions of calcium fluoride in four different concentrations. This paper has the objective to characterize the dust that results from this process, verifying the influence of the temperature and the concentration of calcium fluoride in the briquette in the morphology and chemical composition of the new dust, determining the optimal conditions for the recovery of the zinc content of the dust. This newly generated dust was analyzed in an Scanning Electronic Microscope, used to capture micrographs and chemical composition by EDS. The micrographs show that the temperature and the calcium fluoride concentration interfere in the way the dust particles agglomerate. Chemical analysis points that the higher zinc recuperation occurrs in the experiments at 1500°C with 7% addition of calcium fluoride.

30 CFR 74.7 - Design and construction requirements.

Science.gov (United States)

2010-07-01

... shall measure respirable coal mine dust concentrations accurately, as specified under § 74.8, for an end... 15.1 through 15.407 (FCC Radio Frequency Devices). Persons must proceed in accordance with IEEE Std... CPDM shall be designed and constructed to remain safe and measure respirable coal mine dust...

Human exposure to brominated flame retardants through dust in different indoor environments: Identifying the sources of concentration differences in hair from men and women.

Science.gov (United States)

Li, Junqi; Dong, Zheng; Wang, Ying; Bao, Junsong; Yan, Yijun; Liu, Anming; Jin, Jun

2018-08-01

Brominated flame retardants (BFRs) can accumulate in humans and are associated with adverse health effects. The study was conducted to determine the differences in Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardant (Alt-BFR) concentrations between men and women. We analyzed hair samples from 14 male and 20 female university students, paired dust samples from their dormitories (10 for males and 8 for females), and six dust samples from university teaching buildings. The total PBDE concentrations in hair from females were significantly (three times) higher (p = 0.012) than that from males (means 372 and 109 ng/g, respectively). The mean total PBDE concentrations in classroom and dormitory dust were 36100 and 2012 ng/g, respectively. The PBDE patterns were different in the male and female hair samples, as were the patterns in the classroom and dormitory dust. There are no reports concerning human exposure to BFRs through dust that was assessed considering academic and residential environments simultaneously. The differences between BFR exposure for males and females and the differences between BFR concentrations in hair samples from males and females were consistent for 71.4% of the compounds. However, using only dormitory dust in the calculations gave consistent differences only for 28.6% of the compounds, suggesting that the BFR concentration differences in hair were mainly because females spent much more time than males in classrooms. Copyright © 2018 Elsevier Ltd. All rights reserved.

Correlation between Yellow Dust and Radioactivity

Energy Technology Data Exchange (ETDEWEB)

AIZaabia, Mouza A [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Byoung-Jik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2015-10-15

In East Asia, yellow dust or Asian Dust (AD) outbreaks are among the largest contributors of wind-blown dust that carry natural and anthropogenic radionuclides and subsequently alter their concentration and distribution throughout the environment. Although the Korean Peninsula has been experiencing AD events since ancient times, the research has tended to focus on the transport routes and characteristics of AD, rather than on its impact on radionuclide activity levels. This paper examines the relationship between radionuclide concentration in the air and the frequency of dusty days in South Korea during AD intrusion events. It also investigates whether increased radionuclide concentration is a function of either more mass or more dust contamination. In this study, significant linear correlations of gamma-emitting radionuclides were found with mass of dust and occurrence frequency of AD. Regardless of the source origin of the dust, {sup 137}Cs and {sup 7}Be concentration primarily depended on dust mass in the filter. Nonetheless, the correlations were greatly distorted in 2011 and in the spring season, particularly the correlations with AD days that were far below that of the correlations obtained for the whole study period. A possible explanation of these conflicting results is that a change in the dust source could appreciably alter the concentration, deposition, and distribution of airborne radionuclides.

Effect of Simvastatin, Coenzyme Q10, Resveratrol, Acetylcysteine and Acetylcarnitine on Mitochondrial Respiration.

Science.gov (United States)

Fišar, Z; Hroudová, J; Singh, N; Kopřivová, A; Macečková, D

2016-01-01

Some therapeutic and/or adverse effects of drugs may be related to their effects on mitochondrial function. The effects of simvastatin, resveratrol, coenzyme Q10, acetylcysteine, and acetylcarnitine on Complex I-, Complex II-, or Complex IV-linked respiratory rate were determined in isolated brain mitochondria. The protective effects of these biologically active compounds on the calcium-induced decrease of the respiratory rate were also studied. We observed a significant inhibitory effect of simvastatin on mitochondrial respiration (IC50 = 24.0 μM for Complex I-linked respiration, IC50 = 31.3 μM for Complex II-linked respiration, and IC50 = 42.9 μM for Complex IV-linked respiration); the inhibitory effect of resveratrol was found at very high concentrations (IC50 = 162 μM for Complex I-linked respiration, IC50 = 564 μM for Complex II-linked respiration, and IC50 = 1454 μM for Complex IV-linked respiration). Concentrations required for effective simvastatin- or resveratrol-induced inhibition of mitochondrial respiration were found much higher than concentrations achieved under standard dosing of these drugs. Acetylcysteine and acetylcarnitine did not affect the oxygen consumption rate of mitochondria. Coenzyme Q10 induced an increase of Complex I-linked respiration. The increase of free calcium ions induced partial inhibition of the Complex I+II-linked mitochondrial respiration, and all tested drugs counteracted this inhibition. None of the tested drugs showed mitochondrial toxicity (characterized by respiratory rate inhibition) at drug concentrations achieved at therapeutic drug intake. Resveratrol, simvastatin, and acetylcarnitine had the greatest neuroprotective potential (characterized by protective effects against calcium-induced reduction of the respiratory rate).

Paleo-dust insights onto dust-climate interactions

Science.gov (United States)

Albani, S.; Mahowald, N. M.

2017-12-01

Mineral dust emissions are affected by changing climate conditions, and in turn dust impacts the atmospheric radiation budget, clouds and biogeochemical cycles. Climate and public health dust-related issues call for attention on the fate of the dust cycle in the future, and the representation of the dust cycle is now part of the strategy of the Paleoclimate Modelling Intercomparison Project phase 4 and the Coupled Model Intercomparison Project phase 6 (PMIP4-CMIP6). Since mineral aerosols are one of the most important natural aerosols, understanding past dust responses to climate in the paleoclimate will allow us to better understand mineral aerosol feedbacks with climate and biogeochemistry in the Anthropocene. Modern observations and paleoclimate records offer the possibility of multiple, complementary views on the global dust cycle, and allow to validate and/or constrain the numerical representation of dust in climate and Earth system models. We present our results from a set of simulations with the Community Earth System Model for different climate states, including present and past climates such as the pre-industrial, the mid-Holocene and the Last Glacial Maximum. A set of simulations including a prognostic dust cycle was thoroughly compared with a wide set of present day observations from different platforms and regions, in order to realistically constrain the magnitude of dust load, surface concentration, deposition, optical properties, and particle size distributions. The magnitude of emissions for past climate regimes was constrained based on compilations of paleodust mass accumulation rates and size distributions, as well as based on information on dust provenance. The comparison with a parallel set of simulations without dust allows estimating the impacts of dust on surface climate. We analyze impacts of dust on the mean and variability of surface temperature and precipitation in each climate state, as well as the impacts that changing dust emissions had

Spatial and temporal shifts in gross primary productivity, respiration, and nutrient concentrations in urban streams impacted by wastewater treatment plant effluent

Science.gov (United States)

Ledford, S. H.; Toran, L.

2017-12-01

Impacts of wastewater treatment plant effluent on nutrient retention and stream productivity are highly varied. The working theory has been that large pulses of nutrients from plants may hinder in-stream nutrient retention. We evaluated nitrate, total dissolved phosphorus, and dissolved oxygen in Wissahickon Creek, an urban third-order stream in Montgomery and Philadelphia counties, PA, that receives effluent from four wastewater treatment plants. Wastewater treatment plant effluent had nitrate concentrations of 15-30 mg N/L and total dissolved phosphorus of 0.3 to 1.8 mg/L. Seasonal longitudinal water quality samples showed nitrate concentrations were highest in the fall, peaking at 22 mg N/L, due to low baseflow, but total dissolved phosphorous concentrations were highest in the spring, reaching 0.6 mg/L. Diurnal dissolved oxygen patterns above and below one of the treatment plants provided estimates of gross primary productivity (GPP) and ecosystem respiration (ER). A site 1 km below effluent discharge had higher GPP in April (80 g O2 m-2 d-1) than the site above the plant (28 g O2 m-2 d-1). The pulse in productivity did not continue downstream, as the site 3 km below the plant had GPP of only 12 g O2 m-2 d-1. Productivity fell in June to 1-2 g O2 m-2 d-1 and the differences in productivity above and below plants were minimal. Ecosystem respiration followed a similar pattern in April, increasing from -17 g O2 m-2 d-1 above the plant to -47 g O2 m-2 d-1 1 km below the plant, then decreasing to -8 g O2 m-2 d-1 3 km below the plant. Respiration dropped to -3 g O2 m-2 d-1 above the plant in June but only fell to -9 to -10 g O2 m-2 d-1 at the two downstream sites. These findings indicate that large nutrient pulses from wastewater treatment plants spur productivity and respiration, but that these increases may be strongly seasonally dependent. Examining in-stream productivity and respiration is critical in wastewater impacted streams to understanding the seasonal and

β Absorption dust concentration monitor system based on the PLC

International Nuclear Information System (INIS)

Lian Dexing; Zhou Xiuliang; Liu Liyan; Li Zonglun; Cao Guanghui; Mao Wanchong

2011-01-01

To provide an on-line automatic system for dust concentration monitor is the purpose of this design.The system based on β-ray-absorption-method,employing PLC (Programmable Logic Controller) control technology, is presented. The user input parameter setup,the data acquisition and processing, and the communication with computer can be effectively regulated using the advanced PLC control technology. It has the features of high reliability, easy operation and easy maintenance, and the ability to monitor remotely. Measurement range: 0.1-1500 mg/m 3 , Accuracy: ±9%. The structure,working principle, electric circuit and software development of the system are introduced in detail. (authors)

30 CFR 70.2 - Definitions.

Science.gov (United States)

2010-07-01

.... L. 95-164. (b) Active workings means any place in a coal mine where miners are normally required to... § 70.202 (Certified person; sampling) to take respirable dust samples required by this part or... maintenance and calibration of respirable dust sampling equipment as required by this part. (d) Concentration...

30 CFR 71.2 - Definitions.

Science.gov (United States)

2010-07-01

... surface coal mine or the surface work area of an underground coal mine where miners are normally required... with § 71.202 (Certified person; sampling) to take respirable dust samples required by this part or... maintenance and calibration of respirable dust sampling equipment as required by this part. (d) Concentration...

30 CFR 70.201 - Sampling; general requirements.

Science.gov (United States)

2010-07-01

...; general requirements. (a) Each operator shall take respirable dust samples of the concentration of respirable dust in the active workings of the mine as required by this part with a sampling device approved... Personal Sampler Units) of this title. (b) Sampling devices shall be worn or carried directly to and from...

Measurement of nicotine in household dust

International Nuclear Information System (INIS)

Kim, Sungroul; Aung, Ther; Berkeley, Emily; Diette, Gregory B.; Breysse, Patrick N.

2008-01-01

An analytical method of measuring nicotine in house dust was optimized and associations among three secondhand smoking exposure markers were evaluated, i.e., nicotine concentrations of both house dust and indoor air, and the self-reported number of cigarettes smoked daily in a household. We obtained seven house dust samples from self-reported nonsmoking homes and 30 samples from smoking homes along with the information on indoor air nicotine concentrations and the number of cigarettes smoked daily from an asthma cohort study conducted by the Johns Hopkins Center for Childhood Asthma in the Urban Environment. House dust nicotine was analyzed by isotope dilution gas chromatography-mass spectrometry (GC/MS). Using our optimized method, the median concentration of nicotine in the dust of self-reported nonsmoking homes was 11.7 ng/mg while that of smoking homes was 43.4 ng/mg. We found a substantially positive association (r=0.67, P<0.0001) between house dust nicotine concentrations and the numbers of cigarettes smoked daily. Optimized analytical methods showed a feasibility to detect nicotine in house dust. Our results indicated that the measurement of nicotine in house dust can be used potentially as a marker of longer term SHS exposure

Hygienic assessment of asbestos containing dust in the air of the working zone at thermal power plants

Directory of Open Access Journals (Sweden)

Moshkovskiy V.E.

2016-09-01

Full Text Available Asbestos and artificial mineral fibers were used actively at thermal power plants (TPP as heat insulation of pipes, seal plates, electrical insulation, etc. But content of asbestos fibers in the air of working zone at TPP was not registered to date. Therefore, aim of the work was to assess asbestos containing dust in the air of working zone at steam turbine and gas turbine TPP in the east region of the country. It was found that old insulation at TPP is mixture of asbestoses that contains chrysotile asbestos and traces of amphibole asbestoses – crocidolite and anthophyllite. In the majority of investigated workplaces at the steam turbine TPP significant dust generation with exceed of maximum one-time exposure limits (2 mg/m3 was observed. Concentration of respirable fibers in the air of working zone in all workplaces did not exceed actual hygienic standard (1 fiber/cm3.

Concentration Levels, Pollution Characteristics and Potential Ecological Risk of Dust Heavy Metals in the Metropolitan Area of Beijing, China.

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Xiong, Qiulin; Zhao, Wenji; Zhao, Jiayin; Zhao, Wenhui; Jiang, Lei

2017-09-30

This study aims to investigate the concentration levels, pollution characteristics and the associated potential ecological risks of the heavy metals found in dust in the metropolitan area of Beijing, China during the winter. Dust samples were collected at 49 different spatial locations of Beijing's metropolitan area from November 2013 to January 2014, in which the concentration levels of Cd, Cr, Pb, Cu, Zn, Ni, Co, V, Bi and Mo were measured by Elan DRC II type inductively coupled plasma mass spectrometry (ICP-MS). Test results showed that the concentrations of dust heavy metals Pb, Cr, Cu and Zn in the urban areas (147.1 mg·kg -1 , 195.9 mg·kg -1 , 239.2 mg·kg -1 and 713.2 mg·kg -1 ) were significantly higher than those in the suburbs (91.6 mg·kg -1 , 125.1 mg·kg -1 , 131.9 mg·kg -1 and 514.5 mg·kg -1 ). Enrichment factors and the geo-accumulation index were used to describe the pollution characteristics of dust heavy metals in urban and suburban areas. Results indicated that Zn and Cu were moderately polluting in both urban and suburban areas, Cd was severely polluting in urban areas and heavily polluting in the suburbs. Furthermore, potential ecological risk assessment revealed that the degrees of ecological harm of dust heavy metals were very strong in both urban and suburban areas, but especially in urban areas. The potential ecological risk of heavy metal Cd, whose single factor of ecological damage was extremely strong, accounted for about 90% of the total ecological risk.

Gravimetric Measurements of Filtering Facepiece Respirators Challenged With Diesel Exhaust.

Science.gov (United States)

Satish, Swathi; Swanson, Jacob J; Xiao, Kai; Viner, Andrew S; Kittelson, David B; Pui, David Y H

2017-07-01

Elevated concentrations of diesel exhaust have been linked to adverse health effects. Filtering facepiece respirators (FFRs) are widely used as a form of respiratory protection against diesel particulate matter (DPM) in occupational settings. Previous results (Penconek A, Drążyk P, Moskal A. (2013) Penetration of diesel exhaust particles through commercially available dust half masks. Ann Occup Hyg; 57: 360-73.) have suggested that common FFRs are less efficient than would be expected for this purpose based on their certification approvals. The objective of this study was to measure the penetration of DPM through NIOSH-certified R95 and P95 electret respirators to verify this result. Gravimetric-based penetration measurements conducted using polytetrafluoroethylene (PTFE) and polypropylene (PP) filters were compared with penetration measurements made with a Scanning Mobility Particle Sizer (SMPS, TSI Inc.), which measures the particle size distribution. Gravimetric measurements using PP filters were variable compared to SMPS measurements and biased high due to adsorption of gas phase organic material. Relatively inert PTFE filters adsorbed less gas phase organic material resulting in measurements that were more accurate. To attempt to correct for artifacts associated with adsorption of gas phase organic material, primary and secondary filters were used in series upstream and downstream of the FFR. Correcting for adsorption by subtracting the secondary mass from the primary mass improved the result for both PTFE and PP filters but this correction is subject to 'equilibrium' conditions that depend on sampling time and the concentration of particles and gas phase hydrocarbons. Overall, the results demonstrate that the use of filters to determine filtration efficiency of FFRs challenged with diesel exhaust produces erroneous results due to the presence of gas phase hydrocarbons in diesel exhaust and the tendency of filters to adsorb organic material. Published by

Dust Creation in CNC Drilling of Wood Composites

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Tomasz Rogoziński

2015-04-01

Full Text Available This paper presents the particle-size distribution of dust created by the drilling of selected wood composites, which was carried out using a CNC machine. The particle-size distribution was studied through two methods. Two analyses were performed: the sieve analysis of samples from the whole mass of collected dust and the laser diffraction analysis of the finest fraction isolated by sieving. The results presented general information about the particle-size distribution of the dust, as well as detailed information on the content of the finest particles. This information revealed that the particles might pose a potential risk to the health of workers employed in the woodworking industry. This potential risk is due to the possibility of their dispersion in the atmosphere surrounding the workplace and their size, which allows them to be respirable. The relationship between the fineness of the dust and the type of wood composite was also tested. Most ultrafine particles are formed during the drilling of fibreboards and are especially produced in traditional wet technology.

Effects of cadmium, zinc, lead, and mercury on respiration and fermentation of Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Grafl, H J; Schwantes, H O

1983-01-01

Zinc and lead did not affect the rate of respiration and fermentation. Concentrations of cadmium higher than 10/sup -7/ M and concentrations of mercury higher than 5 x 10/sup -5/ M significantly reduced the O/sub 2/ consumption and the CO/sub 2/ production. 10/sup -2/ M cadmium and 10/sup -3/ M mercury completely inhibited respiration and fermentation. Low concentrations of mercury inhibited respiration irreversibly and fermentation reversibly. High concentrations of zinc reduced the toxicity of low concentrations of cadmium but they enhanced the effects of high concentrations of cadmium and mercury. No interactions between lead and the other tested heavy metals were observed.

Characterization of the respiration-induced yeast mitochondrial permeability transition pore.

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Bradshaw, Patrick C; Pfeiffer, Douglas R

2013-12-01

When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane, dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable through the yPTP in an industrial yeast strain, Yeast Foam. The presence of oligomycin, an inhibitor of ATP synthase, allowed for respiration-induced mannitol permeability in mitochondria from this strain. Potassium (K+) had varied effects on the respiration-induced yPTP, depending on the concentration of the respiratory substrate added. At low respiratory substrate concentrations K+ inhibited respiration-induced yPTP opening, while at high substrate concentrations this effect diminished. However, at the high respiratory substrate concentrations, the presence of K+ partially prevented phosphate inhibition of yPTP opening. Phosphate was found to inhibit respiration-induced yPTP opening by binding a site on the matrix space side of the inner membrane in addition to its known inhibitory effect of donating protons to the matrix space to prevent the pH change necessary for yPTP opening. The respiration-induced yPTP was also inhibited by NAD, Mg2+, NH4 + or the oxyanion vanadate polymerized to decavanadate. The results demonstrate similar effectors of the respiration-induced yPTP as those previously described for the ATP-induced yPTP and reconcile previous strain-dependent differences in yPTP solute selectivity. Copyright © 2013 John Wiley & Sons, Ltd.

Exposure to inhalable, respirable, and ultrafine particles in welding fume.

Science.gov (United States)

Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

2012-07-01

This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

The Relationship between Aerosol Composition and Concentration and Visual Range on Barbados, West Indies: The Impact of African Dust

Science.gov (United States)

Huang, J.; Prospero, J.; Zhang, C.; Arimoto, R.

2006-12-01

Visual Range (VR) measured at Grantley Adams Airport on Barbados shows a very strong annual cycle with the minimum VR values occurring in June or July. This cycle closely matches the annual cycle of African dust concentrations measured in the trade winds at Barbados (13°15'N, 59°30'W) where observations first began in 1965. In winter, monthly mean VR was typically around 30 km or greater while in summer it frequently dipped below 20 km. This same clear signal is observed in the VR records from near-by islands where the same seasonal cycle of dust would be expected: St. Lucia, Martinique and Trinidad and Tobago. We examined the relationship between VR on Barbados and the concentrations of the three major aerosol constituents that we would expect to have the strongest influence on VR: mineral dust, sea salt, and non-sea- salt sulfate (nss-SO4^{=}). We used VR data for the period from 1973, when measurements first began, up to 2006. We found a large discrepancy between the observed VR at the airport and the VR derived from the Koschmieder equation using literature values for the optical properties of the aerosol components; this simple approach would require a much smaller constant than the commonly-used value, 3.912. We further explored the effects of particle size distribution and relative humidity. During boreal summer when VR is lowest, dust is the dominant supramicron aerosol component and it clearly is the major factor in controlling VR. Nonetheless the submicron fraction also has a comparable impact due to its significantly higher light scattering efficiency. During winter, when there is little or no dust, sea salt aerosol and sulfate are dominant. In this report we focus on the various factors that affect visibility on Barbados especially the role of aerosols dominated by supramicrometer particles. We also consider the effects of other factors such as wind speed and precipitation. Finally, we note that the close relationship between summertime VR and dust

Global Gene Expression Profiling in Lung Tissues of Rat Exposed to Lunar Dust Particles

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Yeshitla, Samrawit A.; Lam, Chiu-Wing; Kidane, Yared H.; Feiveson, Alan H.; Ploutz-Snyder, Robert; Wu, Honglu; James, John T.; Meyers, Valerie E.; Zhang, Ye

2014-01-01

The Moon's surface is covered by a layer of fine, potential reactive dust. Lunar dust contain about 1-2% respirable very fine dust (less than 3 micrometers). The habitable area of any lunar landing vehicle and outpost would inevitably be contaminated with lunar dust that could pose a health risk. The purpose of the study is to analyze the dynamics of global gene expression changes in lung tissues of rats exposed to lunar dust particles. F344 rats were exposed for 4 weeks (6h/d; 5d/wk) in nose-only inhalation chambers to concentrations of 0 (control air), 2.1, 6.8, 21, and 61 mg/m3 of lunar dust. Animals were euthanized at 1 day and 13 weeks after the last inhalation exposure. After being lavaged, lung tissue from each animal was collected and total RNA was isolated. Four samples of each dose group were analyzed using Agilent Rat GE v3 microarray to profile global gene expression of 44K transcripts. After background subtraction, normalization, and log transformation, t tests were used to compare the mean expression levels of each exposed group to the control group. Correction for multiple testing was made using the method of Benjamini, Krieger, and Yekuteli (1) to control the false discovery rate. Genes with significant changes of at least 1.75 fold were identified as genes of interest. Both low and high doses of lunar dust caused dramatic, dose-dependent global gene expression changes in the lung tissues. However, the responses of lung tissue to low dose lunar dust are distinguished from those of high doses, especially those associated with 61mg/m3 dust exposure. The data were further integrated into the Ingenuity system to analyze the gene ontology (GO), pathway distribution and putative upstream regulators and gene targets. Multiple pathways, functions, and upstream regulators have been identified in response to lunar dust induced damage in the lung tissue.

Iron mineralogy and bioaccessibility of dust generated from soils as determined by reflectance spectroscopy and magnetic and chemical properties--Nellis Dunes recreational area, Nevada

Science.gov (United States)

Goldstein, Harland L.; Reynolds, Richard L.; Morman, Suzette A.; Moskowitz, Bruce; Kokaly, Raymond F.; Goossens, Dirk; Buck, Brenda J.; Flagg, Cody; Till, Jessica; Yauk, Kimberly; Berquó, Thelma S.

2013-01-01

Atmospheric mineral dust exerts many important effects on the Earth system, such as atmospheric temperatures, marine productivity, and melting of snow and ice. Mineral dust also can have detrimental effects on human health through respiration of very small particles and the leaching of metals in various organs. These effects can be better understood through characterization of the physical and chemical properties of dust, including certain iron oxide minerals, for their extraordinary radiative properties and possible effects on lung inflammation. Studies of dust from the Nellis Dunes recreation area near Las Vegas, Nevada, focus on characteristics of radiative properties (capacity of dust to absorb solar radiation), iron oxide mineral type and size, chemistry, and bioaccessibility of metals in fluids that simulate human gastric, lung, and phagolysosomal fluids. In samples of dust from the Nellis Dunes recreation area with median grain sizes of 2.4, 3.1, and 4.3 micrometers, the ferric oxide minerals goethite and hematite, at least some of it nanosized, were identified. In one sample, in vitro bioaccessibility experiments revealed high bioaccessibility of arsenic in all three biofluids and higher leachate concentration and bioaccessibility for copper, uranium, and vanadium in the simulated lung fluid than in the phagolysosomal fluid. The combination of methods used here to characterize mineral dust at the Nellis Dunes recreation area can be applied to global dust and broad issues of public health.

A case of extreme particulate matter concentrations over Central Europe caused by dust emitted over the southern Ukraine

Directory of Open Access Journals (Sweden)

W. Birmili

2008-02-01

Full Text Available On 24 March 2007, an extraordinary dust plume was observed in the Central European troposphere. Satellite observations revealed its origins in a dust storm in Southern Ukraine, where large amounts of soil were resuspended from dried-out farmlands at wind gusts up to 30 m s⁻¹. Along the pathway of the plume, maximum particulate matter (PM₁₀ mass concentrations between 200 and 1400 μg m⁻³ occurred in Slovakia, the Czech Republic, Poland, and Germany. Over Germany, the dust plume was characterised by a volume extinction coefficient up to 400 Mm⁻¹ and a particle optical depth of 0.71 at wavelength 0.532 μm. In-situ size distribution measurements as well as the wavelength dependence of light extinction from lidar and Sun photometer measurements confirmed the presence of a coarse particle mode with diameters around 2–3 μm. Chemical particle analyses suggested a fraction of 75% crustal material in daily average PM₁₀ and up to 85% in the coarser fraction PM_10–2.5. Based on the particle characteristics as well as a lack of increased CO and CO₂ levels, a significant impact of biomass burning was ruled out. The reasons for the high particle concentrations in the dust plume were twofold: First, dust was transported very rapidly into Central Europe in a boundary layer jet under dry conditions. Second, the dust plume was confined to a relatively stable boundary layer of 1.4–1.8 km height, and could therefore neither expand nor dilute efficiently. Our findings illustrate the capacity of combined in situ and remote sensing measurements to characterise large-scale dust plumes with a variety of aerosol parameters. Although such plumes from Southern Eurasia seem to occur rather infrequently in Central Europe, its unexpected features highlights the need to improve the description of dust emission, transport and transformation processes needs, particularly when facing the

Road dust from pavement wear and traction sanding

Energy Technology Data Exchange (ETDEWEB)

Kupiainen, K.

2007-07-01

Vehicles affect the concentrations of ambient airborne particles through exhaust emissions, but particles are also formed in the mechanical processes in the tire-road interface, brakes, and engine. Particles deposited on or in the vicinity of the road may be re-entrained, or resuspended, into air through vehicle-induced turbulence and shearing stress of the tires. A commonly used term for these particles is 'road dust'. The processes affecting road dust emissions are complex and currently not well known. Road dust has been acknowledged as a dominant source of PM10 especially during spring in the sub-arctic urban areas, e.g. in Scandinavia, Finland, North America and Japan. The high proportion of road dust in sub-arctic regions of the world has been linked to the snowy winter conditions that make it necessary to use traction control methods. Traction control methods include dispersion of traction sand, melting of ice with brine solutions, and equipping the tires with either metal studs (studded winter tires), snow chains, or special tire design (friction tires). Several of these methods enhance the formation of mineral particles from pavement wear and/or from traction sand that accumulate in the road environment during winter. When snow and ice melt and surfaces dry out, traffic-induced turbulence makes some of the particles airborne. A general aim of this study was to study processes and factors underlying and affecting the formation and emissions of road dust from paved road surfaces. Special emphasis was placed on studying particle formation and sources during tire road interaction, especially when different applications of traction control, namely traction sanding and/or winter tires were in use. Respirable particles with aerodynamic diameter below 10 micrometers (PM10) have been the main concern, but other size ranges and particle size distributions were also studied. The following specific research questions were addressed: (i) How do traction

The Continuous Monitoring of Desert Dust using an Infrared-based Dust Detection and Retrieval Method

Science.gov (United States)

Duda, David P.; Minnis, Patrick; Trepte, Qing; Sun-Mack, Sunny

2006-01-01

Airborne dust and sand are significant aerosol sources that can impact the atmospheric and surface radiation budgets. Because airborne dust affects visibility and air quality, it is desirable to monitor the location and concentrations of this aerosol for transportation and public health. Although aerosol retrievals have been derived for many years using visible and near-infrared reflectance measurements from satellites, the detection and quantification of dust from these channels is problematic over bright surfaces, or when dust concentrations are large. In addition, aerosol retrievals from polar orbiting satellites lack the ability to monitor the progression and sources of dust storms. As a complement to current aerosol dust retrieval algorithms, multi-spectral thermal infrared (8-12 micron) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Meteosat-8 Spinning Enhanced Visible and Infrared Imager (SEVIRI) are used in the development of a prototype dust detection method and dust property retrieval that can monitor the progress of Saharan dust fields continuously, both night and day. The dust detection method is incorporated into the processing of CERES (Clouds and the Earth s Radiant Energy System) aerosol retrievals to produce dust property retrievals. Both MODIS (from Terra and Aqua) and SEVERI data are used to develop the method.

Utilizing adequate intake line curtain air quantities to maintain respirable dust compliance

Energy Technology Data Exchange (ETDEWEB)

Schultz, M.J.; Tomko, D.M.; Rumbaugh, V.E. [United States Dept. of Labor, Mine Safety and Health Administration, Pittsburgh, PA (United States). Safety and Health Technical Center

2010-07-01

Mine operators are obligated to ensure the effectiveness of their dust controls and implement practices to minimize the generation of dust in their mines. The 2 main types of face ventilation are blowing and exhaust ventilation. With blowing face ventilation, intake air is directed behind a line curtain or through ventilation tubing and then discharged from the end of the line curtain toward the working face. This paper presented specific information for mine operators regarding where and when exhausting or blowing ventilation will be used. Mine operators should establish the line curtain for directing the face ventilating air as a specific distance from the point of deepest penetration of the face. The location of curtains where roof bolting is being performed should also be specified. The distance from the face is important to the effectiveness of ventilation. 4 refs., 3 tabs., 2 figs.

Microbes and Microstructure: Dust's Role in the Snowpack Evolution

Science.gov (United States)

Lieblappen, R.; Courville, Z.; Fegyveresi, J. M.; Barbato, R.; Thurston, A.

2017-12-01

Dust is a primary vehicle for transporting microbial communities to polar and alpine snowpacks both through wind distribution (dry deposition) and snowfall events (wet deposition). The resulting microbial community diversity in the snowpack may then resemble the source material properties rather than its new habitat. Dust also has a strong influence on the microstructural properties of snow, resulting in changes to radiative and mechanical properties. As local reductions in snowpack albedo lead to enhanced melting and a heterogeneous snow surface, the microbial communities are also impacted. Here we study the impact of the changing microstructure in the snowpack, its influence on microbial function, and the fate of dust particles within the snow matrix. We seek to quantify the changes in respiration and water availability with the onset of melt. Polar samples were collected from the McMurdo Ice Shelf, Antarctica in February, 2017, while alpine samples were collected from Silverton, CO from October to May, 2017 as part of the Colorado Dust on Snow (CDOS) network. At each site, coincident meteorological data provides temperature, wind, and radiative measurements. Samples were collected immediately following dust deposition events and after subsequent snowpack evolution. We used x-ray micro-computed tomography to quantify the microstructural evolution of the snow, while also imaging the microstructural distribution of the dust within the snow. The dust was then collected and analyzed for chemical and microbial activity.

Quantitative evaluation of the protective effect of respirators

International Nuclear Information System (INIS)

Murata, Mikio

1983-01-01

The present status and related problems of the quantitative evaluation method for respirator efficiency are generally reviewed. As the introduction, the special features of various types of respirators are summarized, and the basic concept of leakage and the protection factor are explained. As for the quantitative measurement of the protective efficiency, the features of various existing man-test methods such as NaCl aerosol man-test, DOP (dioctyl phthalate) man-test, and SF 6 gas man-test are reviewed and discussed. As the important problems associated with those man-tests, the following aspects are discussed. The measurement of the aerosol concentration within masks; the calculation method for the protection factor; the effect of beards. The examples of measuring the protection factor are also explained for the following respirator systems: half mask respirator with a high efficiency filter; full face mask respirator with a high efficiency filter; demand mode and pressure-demand mode respirators; and mound suit with suspenders. Finally, the outline of the manual of respiratory protection published by NRC in 1976 is briefly reviewed. (Aoki, K.)

Simplified pressure method for respirator fit testing.

Science.gov (United States)

Han, D; Xu, M; Foo, S; Pilacinski, W; Willeke, K

1991-08-01

A simplified pressure method has been developed for fit testing air-purifying respirators. In this method, the air-purifying cartridges are replaced by a pressure-sensing attachment and a valve. While wearers hold their breath, a small pump extracts air from the respirator cavity until a steady-state pressure is reached in 1 to 2 sec. The flow rate through the face seal leak is a unique function of this pressure, which is determined once for all respirators, regardless of the respirator's cavity volume or deformation because of pliability. The contaminant concentration inside the respirator depends on the degree of dilution by the flow through the cartridges. The cartridge flow varies among different brands and is measured once for each brand. The ratio of cartridge to leakflow is a measure of fit. This flow ratio has been measured on human subjects and has been compared to fit factors determined on the same subjects by means of photometric and particle count tests. The aerosol tests gave higher values of fit.

Transcriptional reprogramming and stimulation of leaf respiration by elevated CO2 concentration is diminished, but not eliminated, under limiting nitrogen supply.

Science.gov (United States)

Markelz, R J Cody; Lai, Lisa X; Vosseler, Lauren N; Leakey, Andrew D B

2014-04-01

Plant respiration responses to elevated CO2 concentration ( [CO2 ] ) have been studied for three decades without consensus about the mechanism of response. Positive effects of elevated [CO2 ] on leaf respiration have been attributed to greater substrate supply resulting from stimulated photosynthesis. Negative effects of elevated [CO2 ] on leaf respiration have been attributed to reduced demand for energy for protein turnover assumed to result from lower leaf N content. Arabidopsis thaliana was grown in ambient (370 ppm) and elevated (750 ppm) [CO2 ] with limiting and ample N availabilities. The stimulation of leaf dark respiration was attenuated in limiting N (+12%) compared with ample N supply (+30%). This response was associated with smaller stimulation of photosynthetic CO2 uptake, but not interactive effects of elevated CO2 and N supply on leaf protein, amino acids or specific leaf area. Elevated [CO2 ] also resulted in greater abundance of transcripts for many components of the respiratory pathway. A greater transcriptional response to elevated [CO2 ] was observed in ample N supply at midday versus midnight, consistent with reports that protein synthesis is greatest during the day. Greater foliar expression of respiratory genes under elevated [CO2 ] has now been observed in diverse herbaceous species, suggesting a widely conserved response. © 2013 John Wiley & Sons Ltd.

Organic fuels for respiration in tropical river systems

Science.gov (United States)

Ward, N.; Keil, R. G.; Richey, J. E.; Krusche, A. V.; Medeiros, P. M.

2011-12-01

Watershed-derived organic matter is thought to provide anywhere from 30-90% of the organic matter in rivers (e.g. Hernes et al 2008; Spencer et al 2010). The most abundant biochemicals on land are cellulose, hemicelluloses, and lignin. Combined, they represent as much as 80% of the biomass in a typical forest and as much as 60% of the biomass in a typical field (natural or crop)(Bose et al 2009; Bridgeman et al., 2007; Hu and Zu 2006; Martens et al 2004). They are often assumed to be refractory and hard to degrade, but this assumption is at odds with virtually all observations: soils and marine sediments are not accumulating vast amounts of these compounds (Hedges and Oades, 1997), and degradation experiments suggest that cellulose, hemicelluloses and lignin are reactive and likely to be important fuels for respiration (Benner, 1991; Haddad et al, 1992; Dittmar et al, 2001; Otto and Simpson, 2006). During several trips to the lower Amazon River, incubation experiments were performed in which the biological degradation of lignin phenols was observed in order to assess the contribution of microbial respiration of terrestrially-derived macromolecules to gross respiration and CO2 gas evasion rates. Both particulate and dissolved lignin concentrations decreased by ~40% after being incubated in the dark for 5-7 days, indicating a turnover time of the entire lignin pool of 12-18 days. These results shift the paradigm that lignocellulose derived OM is highly recalcitrant, and indicate that microbial respiration of lignocellulose may play a larger role in total respiration rates/CO2 outgassing than previously thought. A simple mass balance calculation was done to test whether microbial degradation alone could explain the lignin data observed in the field. First, a theoretical particulate lignin concentration for Macapa was calculated based on the observed data at Obidos. The measured rate of particulate lignin degradation was multiplied by the transit time of water from

EXPERIMENTAL SUBSTANTIATION OF PERMEABILIZED HEPATOCYTES MODEL FOR INVESTIGATION OF MITOCHONDRIA IN SITU RESPIRATION.

Science.gov (United States)

Merlavsky, V M; Manko, B O; Ikkert, O V; Manko, V V

2015-01-01

To verify experimentally the model of permeabilized hepatocytes, the degree of cell permeability was assessed using trypan blue and polarographycally determined cell respiration rate upon succinate (0.35 mM) and a-ketoglutarate (1 mM) oxidation. Oxidative phosphorylation was stimulated by ADP (750 μM). Hepatocyte permeabilization depends on digitonin concentraion in medium and on the number of cells in suspension. Thus, the permeabilization of 0.9-1.7 million cells/ml was completed by 25 μg/ml of digitonin, permeabilization of 2.0-3.0 million cells/ml--by 50 μg/ml of digitonin and permeabilization of 4.0-5.6 million cells/ml--by 100 μg/ml. Thus, the higher is the suspension density, the higher digitonin concentration is required. Treatment of hepatocytes with digitonin resulted in a decrease of endogenous respiration rate to a minimum upon 20-22 μg of digitonin per 1 million cells. Supplementation of permeabilized hepatocytes with α-ketoglutarate maintained stable respiration rate, on the level higher than endogenous respiration at the corresponding digitonin concentration, unlike the intact cells. Respiration rate of permeabilized hepatocytes at the simultaneous addition of α-ketoglutarate and ADP increased to the level of intact cell respiration, irrespective of digitonin concentration. Addition of solely succinate and especially succinate plus ADP markedly intensified the respiration of permeabilized hepatocytes to the level higher than that of intact cells. The dependence of succinate-stimulated respiration on digitonin concentration reached maximum at 20-22 αg of digitonin per 1 million cells. Optimal ratio of digitonin amount and the cell number in suspension is expected to be different in various tissues.

Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings.

Science.gov (United States)

Beamer, P I; Sugeng, A J; Kelly, M D; Lothrop, N; Klimecki, W; Wilkinson, S T; Loh, M

2014-05-01

Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites.

Experimental determination of the unattached radon daughter fraction and dust size distribution in some Canadian uranium mines

International Nuclear Information System (INIS)

Bigu, J.; Kirk, J.

1982-01-01

The unattached radon daughter fraction has been experimentally determined in some Canadian uranium mines. Two experimental methods have been used, the wire screen method and a diffusion sampler based on Mercer's theory of diffusional deposition on parallel circular plates. Experiments were conducted in 'non-diesel' and 'diesel' areas of the mines, i.e. locations where mining was done with diesel machinery. Unattached fractions ranged from about 2-8 per cent for non-diesel area. For diesel areas the unattached fraction was substantially lower, less than about one per cent. The aerosol concentration in the range 0.0015 - 0.13 μm was measured with a condensation nuclei counter. Dust concentration was determined with conventional samplers. Particle size distribution in the respirable range was determined with a fine particle spectrometer in conjunction with eriometric techniques

From dust to dose: Effects of forest disturbance on increased inhalation exposure.

Science.gov (United States)

Whicker, Jeffrey J; Pinder, John E; Breshears, David D; Eberhart, Craig F

2006-09-15

Ecosystem disturbances that remove vegetation and disturb surface soils are major causes of excessive soil erosion and can result in accelerated transport of soils contaminated with hazardous materials. Accelerated wind erosion in disturbed lands that are contaminated is of particular concern because of potential increased inhalation exposure, yet measurements regarding these relationships are lacking. The importance of this was highlighted when, in May of 2000, the Cerro Grande fire burned over roughly 30% of Los Alamos National Laboratory (LANL), mostly in ponderosa pine (Pinus ponderosa) forest, and through areas with soils containing contaminants, particularly excess depleted and natural uranium. Additionally, post-fire thinning was performed in burned and unburned forests on about 25% of LANL land. The first goal of this study was to assess the potential for increased inhalation dose from uranium contaminated soils via wind-driven resuspension of soil following the Cerro Grande Fire and subsequent forest thinning. This was done through analysis of post-disturbance measurements of uranium air concentrations and their relationships with wind velocity and seasonal vegetation cover. We found a 14% average increase in uranium air concentrations at LANL perimeter locations after the fire, and the greatest air concentrations occurred during the months of April-June when wind velocities are highest, no snow cover, and low vegetation cover. The second goal was to develop a methodology to assess the relative contribution of each disturbance type towards increasing public and worker exposure to these resuspended soils. Measurements of wind-driven dust flux in severely burned, moderately burned, thinned, and unburned/unthinned forest areas were used to assess horizontal dust flux (HDF) in these areas. Using empirically derived relationships between measurements of HDF and respirible dust, coupled with onsite uranium soil concentrations, we estimate relative increases in

Penetration of asbestos fibers in respirator filters

International Nuclear Information System (INIS)

Cheng, Yung-Sung; Pearson, S.D.; Rohrbacher, K.D.; Yeh, Hsu-Chi.

1994-01-01

Currently, the health risks associated with asbestos have restricted its use and created a growing asbestos abatement industry with a need for respirator filters that are effective for worker protection. The main purpose of this project is to determine the influence of fiber size, electrostatic charge, and flow rate on the penetration of asbestos fibers in respirator filter cartridges. The study includes four types of filters each tested at two flow rates: the AO-R57A, a dual cartridge HEPA filter tested at 16 and 42.5 L/min; the MSA-S, a dust and mist filter tested at 16 and 42.5 L/min; the MSA-A power filter tested at 32 and 85 L/min; and the 3M-8710, a low-efficiency disposable face mask filter tested at 32 and 85 L/min. The three types of asbestos fibers used (amosite, crocidolite, and chrysotile) ranged in length from 0.04-0.5 μm and in aspect ratio (ratio of length to diameter) from 3 to 60. The fibers were used in both charged and neutralized forms. The results from amosite fibers are reported here

Normal and anomalous diffusion in fluctuations of dust concentration nearby emission source

Science.gov (United States)

Szczurek, Andrzej; Maciejewska, Monika; Wyłomańska, Agnieszka; Sikora, Grzegorz; Balcerek, Michał; Teuerle, Marek

2018-02-01

Particulate matter (PM) is an important component of air. Nowadays, major attention is payed to fine dust. It has considerable environmental impact, including adverse effect on human health. One of important issues regarding PM is the temporal variation of its concentration. The variation contains information about factors influencing this quantity in time. The work focuses on the character of PM concentration dynamics indoors, in the vicinity of emission source. The objective was to recognize between the homogeneous or heterogeneous dynamics. The goal was achieved by detecting normal and anomalous diffusion in fluctuations of PM concentration. For this purpose we used anomalous diffusion exponent, β which was derived from Mean Square Displacement (MSD) analysis. The information about PM concentration dynamics may be used to design sampling strategy, which serves to attain representative information about PM behavior in time. The data analyzed in this work was collected from single-point PM concentration monitoring in the vicinity of seven emission sources in industrial environment. In majority of cases we observed heterogeneous character of PM concentration dynamics. It confirms the complexity of interactions between the emission sources and indoor environment. This result also votes against simplistic approach to PM concentration measurement indoors, namely their occasional character, short measurement periods and long term averaging.

Personal exposure to inhalable cement dust among construction workers.

Science.gov (United States)

Peters, Susan; Thomassen, Yngvar; Fechter-Rink, Edeltraud; Kromhout, Hans

2009-01-01

Objective- A case study was carried out to assess cement dust exposure and its determinants among construction workers and for comparison among workers in cement and concrete production.Methods- Full-shift personal exposure measurements were performed and samples were analysed for inhalable dust and its cement content. Exposure variability was modelled with linear mixed models.Results- Inhalable dust concentrations at the construction site ranged from 0.05 to 34 mg/m(3), with a mean of 1.0 mg/m(3). Average concentration for inhalable cement dust was 0.3 mg/m(3) (GM; range 0.02-17 mg/m(3)). Levels in the ready-mix and pre-cast concrete plants were on average 0.5 mg/m(3) (GM) for inhalable dust and 0.2 mg/m(3) (GM) for inhalable cement dust. Highest concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM = 55 mg/m(3); inhalable cement dust GM = 33 mg/m(3)) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages during reinforcement work and pouring. Most likely other sources were contributing to dust concentrations, particularly at the construction site. Within job groups, temporal variability in exposure concentrations generally outweighed differences in average concentrations between workers. 'Using a broom', 'outdoor wind speed' and 'presence of rain' were overall the most influential factors affecting inhalable (cement) dust exposure.Conclusion- Job type appeared to be the main predictor of exposure to inhalable (cement) dust at the construction site. Inhalable dust concentrations in cement production plants, especially during cleaning tasks, are usually considerably higher than at the construction site.

Grain dust and the lungs.

Science.gov (United States)

Chan-Yeung, M.; Ashley, M. J.; Grzybowski, S.

1978-01-01

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler's lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust. Images p1272-a PMID:348288

Emphysema and pulmonary impairment in coal miners: Quantitative relationship with dust exposure and cigarette smoking

Science.gov (United States)

Kuempel, E. D.; Vallyathan, V.; Green, F. H. Y.

2009-02-01

Coal miners have been shown to be at increased risk of developing chronic obstructive pulmonary diseases including emphysema. The objective of this study was to determine whether lifetime cumulative exposure to respirable coal mine dust is a significant predictor of developing emphysema at a clinically-relevant level of severity by the end of life, after controlling for cigarette smoking and other covariates. Clinically-relevant emphysema severity was determined from the association between individuals' lung function during life (forced expiratory volume in one second, FEV1, as a percentage of predicted normal values) and emphysema severity at autopsy (as the proportion of lung tissue affected). In a logistic regression model, cumulative exposure to respirable coal mine dust was a statistically significant predictor of developing clinically-relevant emphysema severity, among both ever-smokers and never-smokers. The odds ratio for developing emphysema associated with FEV1 <80% at the cohort mean cumulative coal dust exposure (87 mg/m3 x yr) was 2.30 (1.46-3.64, 95% confidence limits), and at the cohort mean cigarette smoking (among smokers: 42 pack-years) was 1.95 (1.39-2.79).

Emphysema and pulmonary impairment in coal miners: quantitative relationship with dust exposure and cigarette smoking

Energy Technology Data Exchange (ETDEWEB)

E.D. Kuempel; V. Vallyathan; F.H.Y. Green [National Institute for Occupational Safety and Health, Cincinnati, OH (United States)

2009-07-01

Coal miners have been shown to be at increased risk of developing chronic obstructive pulmonary diseases including emphysema. The objective of this study was to determine whether lifetime cumulative exposure to respirable coal mine dust is a significant predictor of developing emphysema at a clinically-relevant level of severity by the end of life, after controlling for cigarette smoking and other covariates. Clinically-relevant emphysema severity was determined from the association between individuals' lung function during life (forced expiratory volume in one second, FEV{sub 1}, as a percentage of predicted normal values) and emphysema severity at autopsy (as the proportion of lung tissue affected). In a logistic regression model, cumulative exposure to respirable coal mine dust was a statistically significant predictor of developing clinically-relevant emphysema severity, among both ever-smokers and never-smokers. The odds ratio for developing emphysema associated with FEV1 <80% at the cohort mean cumulative coal dust exposure (87 mg/m{sup 3} x yr) was 2.30 (1.46-3.64, 95% confidence limits), and at the cohort mean cigarette smoking (among smokers: 42 pack-years) was 1.95 (1.39-2.79). 20 refs., 2 figs., 2 tabs.

Emphysema and pulmonary impairment in coal miners: Quantitative relationship with dust exposure and cigarette smoking

Energy Technology Data Exchange (ETDEWEB)

Kuempel, E D [National Institute for Occupational Safety and Health, Education and Information Division, Risk Evaluation Branch, Cincinnati, Ohio (United States); Vallyathan, V [National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Pathology and Physiology Research Branch, Morgantown, West Virginia (United States); Green, F H Y, E-mail: ekuempel@cdc.go [Department of Pathology, Faculty of Medicine, University of Calgary, Calgary, Alberta (Canada)

2009-02-01

Coal miners have been shown to be at increased risk of developing chronic obstructive pulmonary diseases including emphysema. The objective of this study was to determine whether lifetime cumulative exposure to respirable coal mine dust is a significant predictor of developing emphysema at a clinically-relevant level of severity by the end of life, after controlling for cigarette smoking and other covariates. Clinically-relevant emphysema severity was determined from the association between individuals' lung function during life (forced expiratory volume in one second, FEV{sub 1}, as a percentage of predicted normal values) and emphysema severity at autopsy (as the proportion of lung tissue affected). In a logistic regression model, cumulative exposure to respirable coal mine dust was a statistically significant predictor of developing clinically-relevant emphysema severity, among both ever-smokers and never-smokers. The odds ratio for developing emphysema associated with FEV{sub 1} <80% at the cohort mean cumulative coal dust exposure (87 mg/m{sup 3} x yr) was 2.30 (1.46-3.64, 95% confidence limits), and at the cohort mean cigarette smoking (among smokers: 42 pack-years) was 1.95 (1.39-2.79).

Personal exposure to inhalable cement dust among construction workers

International Nuclear Information System (INIS)

Peters, Susan; Kromhout, Hans; Thomassen, Yngvar; Fechter-Rink, Edeltraud

2009-01-01

A case study was carried out in 2006-2007 to assess the actual cement dust exposure among construction workers involved in a full-scale construction project and as a comparison among workers involved in various stages of cement and concrete production. Full-shift personal exposure measurements were performed for several job types. Inhalable dust and cement dust (based on analysis of elemental calcium) concentrations were determined. Inhalable dust exposures at the construction site ranged from 0.05 to 34 mg/m3, with a mean concentration of 1.0 mg/m3. For inhalable cement dust mean exposure was 0.3 mg/m3 (range 0.02-17 mg/m3). Reinforcement and pouring workers had the lowest average concentrations. Inhalable dust levels in the ready-mix and pre-cast concrete plants were, on average, below 0.5 mg/m3 for inhalable dust and below 0.2 mg/m3 for inhalable cement dust. Highest dust concentrations were measured in cement production, particularly during cleaning tasks (inhalable dust GM=55 mg/m3; inhalable cement dust GM=33 mg/m3) at which point the workers wore personal protective equipment. Elemental measurements showed highest but very variable cement percentages in the cement plant and very low percentages of cement during reinforcement work and pouring.

Exposure to respirable crystalline silica in South African farm workers

International Nuclear Information System (INIS)

Swanepoel, Andrew; Rees, David; Renton, Kevin; Kromhout, Hans

2009-01-01

Although listed in some publications as an activity associated with silica (quartz) exposure, agriculture is not widely recognized as an industry with a potential for silica associated diseases. Because so many people work in agriculture; and because silica exposure and silicosis are associated with serious diseases such as tuberculosis (TB), particular in those immunological compromised by the Human immunodeficiency virus (HIV), silica exposure in agriculture is potentially very important. But in South Africa (SA) very little is known about silica exposure in this industry. The objectives of this project are: (a) to measure inhalable and respirable dust and its quartz content on two typical sandy soil farms in the Free State province of SA for all major tasks done on the farms; and (b) to characterise the mineralogy soil type of these farms. Two typical farms in the sandy soil region of the Free State province were studied. The potential health effects faced by these farm workers from exposure to respirable crystalline silica are discussed.

Temporal Trends in Airborne Dust Concentrations at a Large Chrysotile Mine and its Asbestos-enrichment Factories in the Russian Federation During 1951-2001

NARCIS (Netherlands)

Schonfeld, Sara J; Kovalevskiy, Evgeny V; Feletto, Eleonora; Bukhtiyarov, Igor V; Kashanskiy, Sergey V; Moissonier, Monika; Straif, Kurt; McCormack, Valerie A; Schüz, Joachim; Kromhout, Hans

2017-01-01

Objectives: Mining and processing of chrysotile, an established carcinogen, has been undertaken in Asbest, Russian Federation since the late 1800s. Dust concentrations were routinely recorded at the open-pit mine and its asbestos-enrichment factories. We examined the temporal trends in these dust

Naturally occurring diacetyl and 2,3-pentanedione concentrations associated with roasting and grinding unflavored coffee beans in a commercial setting.

Science.gov (United States)

Gaffney, Shannon H; Abelmann, Anders; Pierce, Jennifer S; Glynn, Meghan E; Henshaw, John L; McCarthy, Lauren A; Lotter, Jason T; Liong, Monty; Finley, Brent L

2015-01-01

Over the last decade, concerns have been raised about potential respiratory health effects associated with occupational exposure to the flavoring additives diacetyl and 2,3-pentanedione. Both of these diketones are also natural components of many foods and beverages, including roasted coffee. To date, there are no published studies characterizing workplace exposures to these diketones during commercial roasting and grinding of unflavored coffee beans. In this study, we measured naturally occurring diacetyl, 2,3-pentanedione, and respirable dust at a facility that roasts and grinds coffee beans with no added flavoring agents. Sampling was conducted over the course of three roasting batches and three grinding batches at varying distances from a commercial roaster and grinder. The three batches consisted of lightly roasted soft beans, lightly roasted hard beans, and dark roasted hard beans. Roasting occurred for 37 to 41 min, and the grinding process took between 8 and 11 min. Diacetyl, 2,3-pentanedione, and respirable dust concentrations measured during roasting ranged from less than the limit of detection (bean/roast combination and sample location, diketone concentrations during grinding were higher than those measured during roasting. During grinding, concentrations decreased with increased distance from the source. Measured concentrations of both diketones were higher during grinding of soft beans than hard beans. The results indicate that airborne concentrations of naturally occurring diacetyl and 2,3-pentanedione associated with unflavored coffee processing: (1) are similar to the concentrations that have been measured in food flavoring facilities; (2) are likely to exceed some recommended short-term occupational exposure limits, but; (3) based on previous analyses of exposure response relationships in animal studies, are far below the concentrations that are expected to cause even minimal responses in the human respiratory tract.

Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis

International Nuclear Information System (INIS)

Koivisto, Antti J.; Aromaa, Mikko; Koponen, Ismo K.; Fransman, Wouter; Jensen, Keld A.; Mäkelä, Jyrki M.; Hämeri, Kaarle J.

2015-01-01

Nanoparticle (particles with diameter ≤100 nm) exposure is recognized as a potentially harmful size fraction for pulmonary particle exposure. During nanoparticle synthesis, the number concentrations in the process room may exceed 10 × 10 6 cm −3 . During such conditions, it is essential that the occupants in the room wear highly reliable high-performance respirators to prevent inhalation exposure. Here we have studied the in-use program protection factor (PPF) of loose-fitting powered air purifying respirators, while workers were coating components with TiO 2 or Cu x O y nanoparticles under a hood using a liquid flame spray process. The PPF was measured using condensation particle counters, an electrical low pressure impactor, and diffusion chargers. The room particle concentrations varied from 4 × 10 6 to 40 × 10 6 cm −3 , and the count median aerodynamic diameter ranged from 32 to 180 nm. Concentrations inside the respirator varied from 0.7 to 7.2 cm −3 . However, on average, tidal breathing was assumed to increase the respirator concentration by 2.3 cm −3 . The derived PPF exceeded 1.1 × 10 6 , which is more than 40 × 10 3 times the respirator assigned protection factor. We were unable to measure clear differences in the PPF of respirators with old and new filters, among two male and one female user, or assess most penetrating particle size. This study shows that the loose-fitting powered air purifying respirator provides very efficient protection against nanoparticle inhalation exposure if used properly

Response of Respiration of Soybean Leaves Grown at Ambient and Elevated Carbon Dioxide Concentrations to Day-to-day Variation in Light and Temperature under Field Conditions

Science.gov (United States)

BUNCE, JAMES A.

2005-01-01

• Background and Aims Respiration is an important component of plant carbon balance, but it remains uncertain how respiration will respond to increases in atmospheric carbon dioxide concentration, and there are few measurements of respiration for crop plants grown at elevated [CO2] under field conditions. The hypothesis that respiration of leaves of soybeans grown at elevated [CO2] is increased is tested; and the effects of photosynthesis and acclimation to temperature examined. • Methods Net rates of carbon dioxide exchange were recorded every 10 min, 24 h per day for mature upper canopy leaves of soybeans grown in field plots at the current ambient [CO2] and at ambient plus 350 µmol mol−1 [CO2] in open top chambers. Measurements were made on pairs of leaves from both [CO2] treatments on a total of 16 d during the middle of the growing seasons of two years. • Key Results Elevated [CO2] increased daytime net carbon dioxide fixation rates per unit of leaf area by an average of 48 %, but had no effect on night-time respiration expressed per unit of area, which averaged 53 mmol m−2 d−1 (1·4 µmol m−2 s−1) for both the ambient and elevated [CO2] treatments. Leaf dry mass per unit of area was increased on average by 23 % by elevated [CO2], and respiration per unit of mass was significantly lower at elevated [CO2]. Respiration increased by a factor of 2·5 between 18 and 26 °C average night temperature, for both [CO2] treatments. • Conclusions These results do not support predictions that elevated [CO2] would increase respiration per unit of area by increasing photosynthesis or by increasing leaf mass per unit of area, nor the idea that acclimation of respiration to temperature would be rapid enough to make dark respiration insensitive to variation in temperature between nights. PMID:15781437

PM10 concentration levels at an urban and background site in Cyprus: the impact of urban sources and dust storms.

Science.gov (United States)

Achilleos, Souzana; Evans, John S; Yiallouros, Panayiotis K; Kleanthous, Savvas; Schwartz, Joel; Koutrakis, Petros

2014-12-01

Air quality in Cyprus is influenced by both local and transported pollution, including desert dust storms. We examined PM10 concentration data collected in Nicosia (urban representative) from April 1, 1993, through December 11, 2008, and in Ayia Marina (rural background representative) from January 1, 1999, through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM10 concentrations, meteorological records, and satellite data were used to identify dust storm days. We investigated long-term trends using a Generalized Additive Model (GAM) after controlling for day of week, month, temperature, wind speed, and relative humidity. In Nicosia, annual PM10 concentrations ranged from 50.4 to 63.8 μg/m3 and exceeded the EU annual standard limit enacted in 2005 of 40 μg/m3 every year A large, statistically significant impact of urban sources (defined as the difference between urban and background levels) was seen in Nicosia over the period 2000-2008, and was highest during traffic hours, weekdays, cold months, and low wind conditions. Our estimate of the mean (standard error) contribution of urban sources to the daily ambient PM10 was 24.0 (0.4) μg/m3. The study of yearly trends showed that PM10 levels in Nicosia decreased from 59.4 μg/m3 in 1993 to 49.0 μg/m3 in 2008, probably in part as a result of traffic emission control policies in Cyprus. In Ayia Marina, annual concentrations ranged from 27.3 to 35.6 μg/m3, and no obvious time trends were observed. The levels measured at the Cyprus background site are comparable to background concentrations reported in other Eastern Mediterranean countries. Average daily PM10 concentrations during desert dust storms were around 100 μg/m3 since 2000 and much higher in earlier years. Despite the large impact ofdust storms and their increasing frequency over time, dust storms were responsible for a small fraction of the exceedances of the daily PM10 limit. Implications: This

30 CFR 70.100 - Respirable dust standards.

Science.gov (United States)

2010-07-01

... mine atmosphere during each shift to which each miner in the active workings of each mine is exposed at... sampling device and in terms of an equivalent concentration determined in accordance with § 70.206 (Approved sampling devices; equivalent concentrations). (b) Each operator shall continuously maintain the...

Air-conditioner filters enriching dust mites allergen.

Science.gov (United States)

Zhan, Xiaodong; Li, Chaopin; Xu, Haifeng; Xu, Pengfei; Zhu, Haibin; Diao, Jidong; Li, Na; Zhao, Beibei

2015-01-01

We detected the concentration of dust mites allergen (Der f1 & Der p1) in the air of different places before and after the starting of air-conditioners in Wuhu City, Anhui, China, and to discuss the relation between the dust mites allergen in air-conditioner filters and the asthma attack. The dust samples were collected from the air-conditioner filters in dining rooms, shopping malls, hotels and households respectively. Concentrations of dust mites major group allergen 1 (Der f 1, Der p1) were detected with enzyme linked immunosorbent assay (ELISA), and the dust mite immune activities were determined by dot-ELISA. The concentration of Der f1 in dining rooms, shopping malls, hotels and households was 1.52 μg/g, 1.24 μg/g, 1.31 μg/g and 1.46 μg/g respectively, and the concentration of Der p1 in above-mentioned places was 1.23 μg/g, 1.12 μg/g, 1.16 μg/g and 1.18 μg/g respectively. The concentration of Der f1 & Der p1 in air was higher after the air-conditioners starting one hours later, and the difference was significant (Pair-conditioner filters can enrich dust mites major group allergen, and the allergens can induce asthma. The air-conditioner filters shall be cleaned or replaced regularly to prevent or reduce accumulation of the dust mites and its allergens.

Adhesion of the clay minerals montmorillonite, kaolinite, and attapulgite reduces respiration of Histoplasma capsulatum.

Science.gov (United States)

Lavie, S; Stotzky, G

1986-01-01

The respiration of three phenotypes of Histoplasma capsulatum, the causal agent of histoplasmosis in humans, was markedly reduced by low concentrations of montmorillonite but was reduced less by even higher concentrations of kaolinite or attapulgite (palygorskite). The reduction in respiration followed a pattern that suggested saturation-type kinetics: an initial sharp reduction that occurred with low concentrations of clay (0.01 to 0.5% [wt/vol]), followed by a more gradual reduction with higher concentrations (1 to 8%). Increases in viscosity (which could impair the movement of O2) caused by the clays were not responsible for the reduction in respiration, and the clays did not interfere with the availability of nutrients. Scanning electron microscopy after extensive washing showed that the clay particles were tightly bound to the hyphae, suggesting that the clays reduced the rate of respiration of H. capsulatum by adhering to the mycelial surface and, thereby, interfered with the movement of nutrients, metabolites, and gases across the mycelial wall.

Comparison of the CAS-POL and IOM samplers for determining the knockdown efficiencies of water sprays on float coal dust.

Science.gov (United States)

Seaman, Clara E; Shahan, Michael R; Beck, Timothy W; Mischler, Steven E

2018-03-01

Float coal dust, generated by mining operations, is distributed throughout mine airways by ventilating air designed to purge gases and respirable dust. Float coal dust poses an explosion hazard in the event of a methane ignition. Current regulation requires the application of inert rock dust in areas subjected to float coal dust in order to mitigate the hazard. An alternate method using water sprays, which have been effective in controlling respirable dust hazards, has been proposed as a way to control float coal dust generated on longwall faces. However, the knockdown efficiency of the proposed water sprays on float coal dust needs to be verified. This study used gravimetric isokinetic Institute of Occupational Medicine (IOM) samplers alongside a real-time aerosol monitor (Cloud Aerosol Spectrometer with polarization; CAS-POL) to study the effects of spray type, operating pressure, and spray orientation on knockdown efficiencies for seven different water sprays. Because the CAS-POL has not been used to study mining dust, the CAS-POL measurements were validated with respect to the IOM samplers. This study found that the CAS-POL was able to resolve the same trends measured by the IOM samplers, while providing additional knockdown information for specific particle size ranges and locations in the test area. In addition, the CAS-POL data was not prone to the same process errors, which may occur due to the handling of the IOM filter media, and was able to provide a faster analysis of the data after testing. This study also determined that pressure was the leading design criteria influencing spray knockdown efficiency, with spray type also having some effect and orientation having little to no effect. The results of this study will be used to design future full-scale float coal dust capture tests involving multiple sprays, which will be evaluated using the CAS-POL.

Dust Effect on The Performance of Optical Wireless Communication System

Directory of Open Access Journals (Sweden)

Fadel Abdul-Zahra Murad

2017-11-01

Full Text Available In this paper wireless optical communication system (FSO is designed through the use of software (Optisystem . The paper also study  the effect of atmospheric dust on the performance of communication system (FSO, the effect of dust concentration on the visibility by taking a different concentrations of dust (9, 20, 40, 60, 80 100, 120 gm / month / m2 . The effect of the visibility on the attenuation of dust concentration on each of these concentrations , and calculate attenuation of dust for the  wavelengths  (784 nm, 1550 nm. The Paper also deals with effect of the transmitted laser  power on the transmitter range (propagation distance where five different values of transmitted laser power (10mw, 20mw, 30mw, 40mw, 50mw are taken  and the study calculates the maximum transmitter range of  each value of the transmitted power under the influence of attenuation atmospheric dust concentrations for each concentration of dust used and also for the two wavelengths (1550nm, 784nm.

A comparative study of health risk of potentially toxic metals in urban and suburban road dust in the most populated city of China

Science.gov (United States)

Shi, Guitao; Chen, Zhenlou; Bi, Chunjuan; Wang, Li; Teng, Jiyan; Li, Yuansheng; Xu, Shiyuan

2011-01-01

Urban and suburban road dust samples were collected in the most populated city of China, Shanghai. Size fractions of dust particles were analyzed; metal levels of the dust were also measured. Human exposure to individual toxic metals through road dust was assessed for both children and adults. The results showed that dust particles from urban and suburban road were presented similar size distribution pattern, with most particles in the range of 100-400 μm. Urban road dust consisted of higher proportions of inhalable, thoracic and respirable particles with increased risk of adverse effects to human. In general, mean grain sizes of urban road dust were smaller than suburban dust. Total organic carbon contents and levels of Pb, Cd, Cu, Zn, Ni, Cr in urban dust were higher than those of suburban dust. But the concentrations of As and Hg from suburban dust were higher, indicting a different main source. The exposure pathway which resulted in the highest level of risk for human exposed to road dust was ingestion of this material, which was followed by dermal contact. Except for some locations, risk values of both cancer and non-cancer obtained in this study were in the receivable range on the whole. Children had greater health risks than adults. The overall risks of non-cancer in urban area were higher than those in suburban area, but the values of cancer in the two areas were comparable. As for the aggregate noncarcinogenic risk, Pb was of most concern regarding the potential occurrence of health impacts. Of the three carcinogenic metals As, Cr and Cd, the only mean risk higher than 10 -6 was Cr, accounting for a great percentage (95%) of the overall risk of cancer. Hence, potentially adverse health effects arising from Pb and Cr in road dust should arouse wide concern.

Dust in planetary nebulae

International Nuclear Information System (INIS)

Mathis, J.S.

1978-01-01

The author's review concentrates on theoretical aspects of dust in planetary nebulae (PN). He considers the questions: how much dust is there is PN; what is its composition; what effects does it have on the ionization structure, on the dynamics of the nebula. (Auth.)

Microbial respiration and gene expression as a function of very low oxygen concentration

DEFF Research Database (Denmark)

Tiano, Laura

and denitrification, were only partially described. In spite of the importance of aerobic respiration as a key process in the global carbon cycle, the available data are still few, and highly biased with respect to season, latitude and depth. The main aims of this Ph.D were to: i) develop and test a highly...... to pure cultures (Manuscript III), in order to assess the response of three species of NOB (Nitrospira defluvvi, N. moscoviensis and Nitrospina gracilis) to low O2 concentrations, and the oxygen regulation on the expression of the terminal oxidases genes in N.moscoviensis. The oxygen affinities...... of these pure cultures were lower than found for natural communities of NOB (apparent Km values~ 1- 4 µM), but higher than the ones from the well-studied opportunistic NOB Nitrobacter. The expression of high-affinity terminal oxidases in these NOB could, however, not be confirmed. Overall the results of this Ph...

Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece

International Nuclear Information System (INIS)

Besis, Athanasios; Katsoyiannis, Athanasios; Botsaropoulou, Elisavet; Samara, Constantini

2014-01-01

Polybrominated Diphenyl Ethers (PBDEs) are ubiquitous in the indoor environment owing to their use in consumer products and various studies around the world have found higher concentrations indoors than outdoors. Central air conditioner (A/C) systems have been widely used in many workplaces, therefore, studying of PBDEs in central A/C filter dust is useful to better understand the occurrences and health implications of PBDEs in indoor environments. The present study examined the occurrence of PBDEs in central A/C filter dust collected from various workplaces (n = 20) in Thessaloniki, Greece. The sum concentrations of 21 target congeners (∑ 21 PBDE) in A/C dust ranged between 84 and 4062 ng g −1 with a median value of 1092 ng g −1 , while BDE-209 was found to be the most abundant BDE congener. The daily intake via dust ingestion of PBDEs estimated for the employees of the occupational settings ranged from 3 to 45 ng day −1 (median 12 ng day −1 ). - Highlights: • PBDEs were investigated in dust of A/C filters in occupational settings in Thessaloniki, Greece. • BDE-209 was found to be the most abundant BDE congener. • High levels of PBDEs were found in a newspaper building, internet cafes and electronic shops. • PBDEs were attributable to the extensive presence and/or usage of electronic devices. • Exposure of employees to PBDEs via indoor dust ingestion was estimated at 12 ng day −1 . - PBDEs were for the first time measured in dust from central A/C filters in workplaces of Greece and their concentrations were used to estimate the non-dietary human exposure

Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis

Energy Technology Data Exchange (ETDEWEB)

Koivisto, Antti J., E-mail: jok@nrcwe.dk [National Research Centre for the Working Environment (Denmark); Aromaa, Mikko [Tampere University of Technology, Department of Physics (Finland); Koponen, Ismo K. [National Research Centre for the Working Environment (Denmark); Fransman, Wouter [TNO (Netherlands); Jensen, Keld A. [National Research Centre for the Working Environment (Denmark); Mäkelä, Jyrki M. [Tampere University of Technology, Department of Physics (Finland); Hämeri, Kaarle J. [University of Helsinki, Department of Physics (Finland)

2015-04-15

Nanoparticle (particles with diameter ≤100 nm) exposure is recognized as a potentially harmful size fraction for pulmonary particle exposure. During nanoparticle synthesis, the number concentrations in the process room may exceed 10 × 10{sup 6} cm{sup −3}. During such conditions, it is essential that the occupants in the room wear highly reliable high-performance respirators to prevent inhalation exposure. Here we have studied the in-use program protection factor (PPF) of loose-fitting powered air purifying respirators, while workers were coating components with TiO{sub 2} or Cu{sub x}O{sub y} nanoparticles under a hood using a liquid flame spray process. The PPF was measured using condensation particle counters, an electrical low pressure impactor, and diffusion chargers. The room particle concentrations varied from 4 × 10{sup 6} to 40 × 10{sup 6} cm{sup −3}, and the count median aerodynamic diameter ranged from 32 to 180 nm. Concentrations inside the respirator varied from 0.7 to 7.2 cm{sup −3}. However, on average, tidal breathing was assumed to increase the respirator concentration by 2.3 cm{sup −3}. The derived PPF exceeded 1.1 × 10{sup 6}, which is more than 40 × 10{sup 3} times the respirator assigned protection factor. We were unable to measure clear differences in the PPF of respirators with old and new filters, among two male and one female user, or assess most penetrating particle size. This study shows that the loose-fitting powered air purifying respirator provides very efficient protection against nanoparticle inhalation exposure if used properly.

Direct-reading inhalable dust monitoring--an assessment of current measurement methods.

Science.gov (United States)

Thorpe, Andrew; Walsh, Peter T

2013-08-01

Direct-reading dust monitors designed specifically to measure the inhalable fraction of airborne dust are not widely available. Current practice therefore often involves comparing the response of photometer-type dust monitors with the concentration measured with a reference gravimetric inhalable sampler, which is used to adjust the dust monitor measurement. However, changes in airborne particle size can result in significant errors in the estimation of inhalable concentration by this method. The main aim of this study was to assess how these dust monitors behave when challenged with airborne dust containing particles in the inhalable size range and also to investigate alternative dust monitors whose response might not be as prone to variations in particle size or that could be adapted to measure inhalable dust concentration. Several photometer-type dust monitors and a Respicon TM, tapered element oscillating microbalance (TEOM) personal dust monitor (PDM) 3600, TEOM 1400, and Dustrak DRX were assessed for the measurement of airborne inhalable dust during laboratory and field trials. The PDM was modified to allow it to sample and measure larger particles in the inhalable size range. During the laboratory tests, the dust monitors and reference gravimetric samplers were challenged inside a large dust tunnel with aerosols of industrial dusts known to present an inhalable hazard and aluminium oxide powders with a range of discrete particle sizes. A constant concentration of each dust type was generated and peak concentrations of larger particles were periodically introduced to investigate the effects of sudden changes in particle size on monitor calibration. The PDM, Respicon, and DataRam photometer were also assessed during field trials at a bakery, joinery, and a grain mill. Laboratory results showed that the Respicon, modified PDM, and TEOM 1400 observed good linearity for all types of dust when compared with measurements made with a reference IOM sampler; the

Reducing dust and allergen exposure in bakeries

Directory of Open Access Journals (Sweden)

Howard J Mason

2017-12-01

Full Text Available Bakers have a continuing high incidence of occupational allergic asthma. In factory bakeries they are exposed not only to flour dust containing allergens, but also improvers whose ingredients enhance the strength and workability of the dough and its speed of rising. Improvers are flour-based but can contain added soya, fungal or bacterial enzymes that are also allergenic, as well as vegetable oil, calcium sulphate/silicate and organic esters. This study investigated the dustiness of the components used in factory bakeries and whether altering improver ingredients could reduce dust and allergen exposure. A standardised rotating drum test was employed on the individual components, as well as a representative improver and three practicable improver modifications by decreasing calcium sulphate, calcium silicate or increasing oil content. Levels of dust, the allergens wheat flour amylase inhibitor (WAAI and soya trypsin inhibitor (STI were measured in the generated inhalable, thoracic and respirable sized fractions. A “scooping and pouring” workplace simulation was also performed. Initial tests showed that dustiness of several wheat flours was relatively low, and even lower for soya flour, but increased in combination with some other improver components. All three improver modifications generally reduced levels of dust, STI and WAAI, but increasing oil content significantly decreased dust and STI in comparison to the standard improver and those improvers with reduced calcium silicate or sulphate. The simulation demonstrated that increased oil content reduced inhalable levels of gravimetric dust, STI and WAAI. Changing improver formulation, such as increasing oil content of flour by a small amount, may represent a simple, practical method of reducing bakery workers’ exposure to dust and allergens where improvers are used. It may be a useful adjunct to engineering control, changes to work practices and appropriate training in reducing the risk to

Concentrations of legacy and novel brominated flame retardants in indoor dust in Melbourne, Australia: An assessment of human exposure.

Science.gov (United States)

McGrath, Thomas J; Morrison, Paul D; Ball, Andrew S; Clarke, Bradley O

2018-04-01

Polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFR) have been used in a range of polymers to inhibit the spread of fires but also have a propensity to migrate out of consumer materials and contaminate indoor dust. In this study, a total of 57 dust samples were collected from 12 homes, eight offices and eight vehicles in Melbourne, Australia and analysed for eight PBDEs (-28, -47, -99, -100, -153, -154, -183 and -209) and seven NBFRs (PBT, PBEB, HBB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) to determine human exposure risks from dust ingestion. Samples were analysed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Legacy and replacement flame retardants were detected in all samples with overall ∑PBDE concentrations ranging from 120 to 1700,000 ng/g (median 2100 ng/g) and ∑NBFRs ranging from 1.1 to 10,000 ng/g (median 1800 ng/g). BDE-209 and DBDPE were the dominant compounds in dust samples, followed by congeners associated with commercial Penta-BDE formulations (-47, -99, -100, -153 and -154) and then EH-TBB of the FireMaster 550 and BZ-54 products. ∑Penta-BDE concentrations were elevated in office samples compared with homes and vehicles, while EH-TBB and BDE-209 measured higher concentrations in vehicles compared with their respective levels in homes and offices. Risk assessment estimates revealed the majority of exposure to occur in the home for both adults and toddlers in the City of Melbourne. Generally, body weight adjusted exposure to PBDEs and NBFRs was predicted to be 1 to 2 orders of magnitude higher for toddlers than adults. Estimated rates of BDE-47, -99, -153 and -209 ingestion were each 2 orders of magnitude or more below the USEPA's prescribed oral reference dose values (RfDs) for typical exposure scenarios. However, exposure rates for BDE-47 and -99 reached as high as 52 and 95% of RfDs, respectively, for adults and 4.4 and 7

Exposure of miners' to ore dust and its long-lived α-emitters in Banduhurang open cast uranium mine, Jharkhand, India

International Nuclear Information System (INIS)

Rana, B.K.; Topno, R.; Kumar, Rajesh; Sahoo, S.K.; Shukla, A.K.; Puranik, V.D.; Tripathi, R.M.

2008-01-01

Monitoring of airborne respirable particulate and its long-lived a -emitters (LLa) of the natural uranium decay series in a highly mechanised open cast uranium mine at Banduhurang is carried out for quantifying the hazard potentials associated with it. Respirable dust in the mine assumes geometric mean (c g ) of 0.71 mg m -3 (AM =0.78 mg m -3 ) and geometric standard deviation (S g ) of 1.5 (A.S.D.=0.30) whereas those for the LLa are 15.97mBq m -3 (A.M. =19.67 mBq m -3 ) and 1.97 (A.S.D.= 12.52) respectively. The specific activity of LLa of respirable dust assumes c g of 22.5 Bq g -1 which is ∼1.9 times higher compared to theoretically computed value for this low ore grade (0.026 U 3 O 8 %) mine. However, the internal radiation exposures attributable to airborne LLa in this mine would constitute merely a small fraction (<1.5%) of annual effective dose limit for mine workers. (author)

Glycolysis Is Dynamic and Relates Closely to Respiration Rate in Stored Sugarbeet Roots

Directory of Open Access Journals (Sweden)

Clarice A. Megguer

2017-05-01

Full Text Available Although respiration is the principal cause of the loss of sucrose in postharvest sugarbeet (Beta vulgaris L., the internal mechanisms that control root respiration rate are unknown. Available evidence, however, indicates that respiration rate is likely to be controlled by the availability of respiratory substrates, and glycolysis has a central role in generating these substrates. To determine glycolytic changes that occur in sugarbeet roots after harvest and to elucidate relationships between glycolysis and respiration, sugarbeet roots were stored for up to 60 days, during which activities of glycolytic enzymes and concentrations of glycolytic substrates, intermediates, cofactors, and products were determined. Respiration rate was also determined, and relationships between respiration rate and glycolytic enzymes and metabolites were evaluated. Glycolysis was highly variable during storage, with 10 of 14 glycolytic activities and 14 of 17 glycolytic metabolites significantly altered during storage. Changes in glycolytic enzyme activities and metabolites occurred throughout the 60 day storage period, but were greatest in the first 4 days after harvest. Positive relationships between changes in glycolytic enzyme activities and root respiration rate were abundant, with 10 of 14 enzyme activities elevated when root respiration was elevated and 9 glycolytic activities static during periods of unchanging respiration rate. Major roles for pyruvate kinase and phosphofructokinase in the regulation of postharvest sugarbeet root glycolysis were indicated based on changes in enzymatic activities and concentrations of their substrates and products. Additionally, a strong positive relationship between respiration rate and pyruvate kinase activity was found indicating that downstream TCA cycle enzymes were unlikely to regulate or restrict root respiration in a major way. Overall, these results establish that glycolysis is not static during sugarbeet root

78 FR 45566 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Coal Mine...

Science.gov (United States)

2013-07-29

... for OMB Review; Comment Request; Coal Mine Dust Sampling Devices ACTION: Notice. SUMMARY: The... information collection request (ICR) titled, ``Coal Mine Dust Sampling Devices,'' to the Office of Management...) determine the concentration of respirable dust in coal mines. CPDMs must be designed and constructed for...

Fipronil and its degradates in indoor and outdoor dust

Science.gov (United States)

Mahler, B.J.; Van Metre, P.C.; Wilson, J.T.; Musgrove, M.; Zaugg, S.D.; Burkhardt, M.R.

2009-01-01

Fipronil is a potent insecticide used for control of termites, fleas, roaches, ants, and other pests. We measured fipronil, fipronil sulfide, and desulfinyl fipronil concentrations in indoor and outdoor dust from 24 residences in Austin, Texas. At least one of these three fipronil compounds was detected in every sample. Fipronil accounted for most of the total fipronil (T-fipronil; fipronil+desulfinyl fipronil+fipronil sulfide), followed by desulfinyl fipronil and fipronil sulfide. Nineteen of 24 samples of indoor dust had T-fipronil concentrations less than 270 ??g/kg; the remaining five had concentrations from 1320 to 14,200 ??g/kg. All three of the residences with a dog on which a flea-control product containing fipronil was used were among the five residences with elevated fipronil concentrations. In outdoor dust, all concentrations of T-fipronil were less than 70??g/kg with one exception (430??g/kg). For every residence, the concentration of T-fipronil in indoor dust exceeded that in outdoor dust, and the median concentration of T-fipronil was 15 times higher indoors than outdoors.

Lead in Chinese villager house dust: Geographical variation and influencing factors

International Nuclear Information System (INIS)

Bi, Xiangyang; Liu, Jinling; Han, Zhixuan; Yang, Wenlin

2015-01-01

House dust has been recognized as an important contributor to Pb exposure of children. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The influences of outdoor soil Pb concentrations, dates of construction, house decoration materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with a median concentration of 42 mg/kg. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decoration materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. Principal component analysis (PCA) confirmed that elemental compositions of the house dust were controlled by both anthropogenic and geogenic sources. Using scanning electron microscopy (SEM), the Pb bearing particles in the house dust were also studied. - Highlights: • Geographical variation in house dust Pb concentrations were observed. • Dust Pb concentrations were not associated with house age and decoration materials. • Soil, coal combustion, and site specific pollution were potential Pb sources. • Pb bearing particles were identified by SEM-EDX. - The variations of Pb in Chinese villager house dust were controlled by outdoor soil, coal combustion, and site specific pollution sources.

Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

Science.gov (United States)

Jarvi, Mickey P; Burton, Andrew J

2013-09-01

The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

Effect of organic synthetic food colours on mitochondrial respiration.

Science.gov (United States)

Reyes, F G; Valim, M F; Vercesi, A E

1996-01-01

Eleven organic synthetic dyes, currently or formerly used as food colours in Brazil, were tested to determine their effect on mitochondrial respiration in mitochondria isolated from rat liver and kidney. The compounds tested were: Erythrosine, Ponceau 4R, Allura Red, Sunset yellow, Tartrazine, Amaranth, Brilliant Blue, Blue, Fast Red E, Orange GGN and Scarlet GN. All food colours tested inhibited mitochondrial respiration (State III respiration, uncoupled) supported either by alpha-ketoglutarate or succinate. This inhibition varied largely, e.g. from 100% to 16% for Erythrosine and Tartrazine respectively, at a concentration of 0.1 mg food colour per mitochondrial protein. Both rat liver and kidney mitochondria showed similar patterns of inhibition among the food colours tested. This effect was dose related and the concentration to give 50% inhibition was determined for some of the dyes. The xanthene dye Erythrosine, which showed the strongest effect, was selected for further investigation on mitochondria in vivo.

A STUDY OF FISCHER 344 RATS EXPOSED TO SILICA DUST FOR SIX MONTHS AT CONCENTRATIONS OF 0, 2, 10 OR 20 MG / M3.

Energy Technology Data Exchange (ETDEWEB)

KUTZMAN,R.S.

1984-02-01

The major objective of this study was to relate the results of a series of functional tests to the compositional and structural alterations in the rat lung induced by subchronic exposure to silica dust. Fischer-344 rats were exposed for 6 hours/day, 5 days/week for 6 months to either 0, 2, 10, or 20 mg SiO{sub 2}/m{sup 3}. The general appearance of the exposed rats was not different from that of the controls. Interestingly, female rats exposed to silica dust, at all tested concentrations, gained more weight than the controls. The lung weight and the lung-to-body weight ratio was greater in the male rats exposed to the highest concentration of silica dust.

Temperature dependence of bulk respiration of crop stands. Measurement and model fitting

International Nuclear Information System (INIS)

Tani, Takashi; Arai, Ryuji; Tako, Yasuhiro

2007-01-01

The objective of the present study was to examine whether the temperature dependence of respiration at a crop-stand scale could be directly represented by an Arrhenius function that was widely used for representing the temperature dependence of leaf respiration. We determined temperature dependences of bulk respiration of monospecific stands of rice and soybean within a range of the air temperature from 15 to 30degC using large closed chambers. Measured responses of respiration rates of the two stands were well fitted by the Arrhenius function (R 2 =0.99). In the existing model to assess the local radiological impact of the anthropogenic carbon-14, effects of the physical environmental factors on photosynthesis and respiration of crop stands are not taken into account for the calculation of the net amount of carbon per cultivation area in crops at harvest which is the crucial parameter for the estimation of the activity concentration of carbon-14 in crops. Our result indicates that the Arrhenius function is useful for incorporating the effect of the temperature on respiration of crop stands into the model which is expected to contribute to a more realistic estimate of the activity concentration of carbon-14 in crops. (author)

Contribution of Root Respiration to Soil Respiration in Sugarcane Plantation in Thailand

OpenAIRE

Wilaiwan Sornpoon; Sebastien Bonnet; Poonpipope Kasemsap; Savitri Garivait

2013-01-01

The understanding on the contribution of root respiration to total soil respiration is still very limited, especially for sugarcane. In this study, trenching experiments in sugarcane plantations were conducted to separate and investigate soil respiration for this crop. The measurements were performed for the whole growing period of 344 days to quantify root respiration. The obtained monitoring data showed that the respiration rate is increasing with the age of the plant, accounting for up to ...

Toxicity of Lunar Dust in Lungs Assessed by Examining Biomarkers in Exposed Mice

Science.gov (United States)

Lam, C.-W.; James, J. T.; Zeidler-Erdely, P. C.; Castranova, V.; Young, S. H.; Quan, C. L.; Khan-Mayberry, N.; Taylor, L. A.

2010-01-01

NASA is contemplating to build an outpost on the Moon for prolonged human habitation and research. The lunar surface is covered by a layer of soil, of which the finest portion is highly reactive dust. Dust samples of respirable sizes were aerodynamically isolated from two lunar soil samples of different maturities (cosmic exposure ages) collected during the Apollo 16 mission. The lunar dust samples, TiO2, or quartz, suspended in normal saline were given to groups of 5 C57 male mice by intrapharyngeal aspiration at 0. 1, 0.3, or 1.0 mg/mouse. Because lunar dust aggregates rapidly in aqueous media, some tests were conducted with dusts suspended in Survanta/saline (1:1). The mice were euthanized 7 or 30 days later, and their lungs were lavaged to assess the presence of toxicity biomarkers in bronchioalveolar lavage fluids. The overall results showed that the two lunar dust samples were similar in toxicity, they were more toxic than T102 , but less toxic than quartz. This preliminary study is a part of the large study to obtain data for setting exposure limits for astronauts living on the Moon

Determination of respirable-sized crystalline silica in different ambient environments in the United Kingdom with a mobile high flow rate sampler utilising porous foams to achieve the required particle size selection

Science.gov (United States)

Stacey, Peter; Thorpe, Andrew; Roberts, Paul; Butler, Owen

2018-06-01

Inhalation of respirable crystalline silica (RCS) can cause diseases including silicosis and cancer. Levels of RCS close to an emission source are measured but little is known about the wider ambient exposure from industry emissions or natural sources. The aim of this work is to report the RCS concentrations obtained from a variety of ambient environments using a new mobile respirable (PM4) sampler. A mobile battery powered high flow rate (52 L min-1) sampler was developed and evaluated for particulate aerosol sampling employing foams to select the respirable particle size fraction. Sampling was conducted in the United Kingdom at site boundaries surrounding seven urban construction and demolition and five sand quarry sites. These are compared with data from twelve urban aerosol samples and from repeat measurements from a base line study at a single rural site. The 50% particle size penetration (d50) through the foam was 4.3 μm. Over 85% of predict bias values were with ±10% of the respirable convention, which is based on a log normal curve. Results for RCS from all construction and quarry activities are generally low with a 95 th percentile of 11 μg m-3. Eighty percent of results were less than the health benchmark value of 3 μg m-3 used in some states in America for ambient concentrations. The power cutting of brick and the largest demolition activities gave the highest construction levels. Measured urban background RCS levels were typically below 0.3 μg m-3 and the median RCS level, at a rural background location, was 0.02 μg m-3. These reported ambient RCS concentrations may provide useful baseline values to assess the wider impact of fugitive, RCS containing, dust emissions into the wider environment.

Asian dust events of April 1998

Science.gov (United States)

Husar, R.B.; Tratt, D.M.; Schichtel, B.A.; Falke, S.R.; Li, F.; Jaffe, D.; Gasso, S.; Gill, T.; Laulainen, N.S.; Lu, F.; Reheis, M.C.; Chun, Y.; Westphal, D.; Holben, B.N.; Gueymard, C.; McKendry, I.; Kuring, N.; Feldman, G.C.; McClain, C.; Frouin, R.J.; Merrill, J.; DuBois, D.; Vignola, F.; Murayama, T.; Nickovic, S.; Wilson, W.E.; Sassen, K.; Sugimoto, N.; Malm, W.C.

2001-01-01

On April 15 and 19, 1998, two intense dust storms were generated over the Gobi desert by springtime low-pressure systems descending from the northwest. The windblown dust was detected and its evolution followed by its yellow color on SeaWiFS satellite images, routine surface-based monitoring, and through serendipitous observations. The April 15 dust cloud was recirculating, and it was removed by a precipitating weather system over east Asia. The April 19 dust cloud crossed the Pacific Ocean in 5 days, subsided to the surface along the mountain ranges between British Columbia and California, and impacted severely the optical and the concentration environments of the region. In east Asia the dust clouds increased the albedo over the cloudless ocean and land by up to 10-20%, but it reduced the near-UV cloud reflectance, causing a yellow coloration of all surfaces. The yellow colored backscattering by the dust eludes a plausible explanation using simple Mie theory with constant refractive index. Over the West Coast the dust layer has increased the spectrally uniform optical depth to about 0.4, reduced the direct solar radiation by 30-40%, doubled the diffuse radiation, and caused a whitish discoloration of the blue sky. On April 29 the average excess surface-level dust aerosol concentration over the valleys of the West Coast was about 20-50 ??g/m3 with local peaks >100 ??g/m3. The dust mass mean diameter was 2-3 ??m, and the dust chemical fingerprints were evident throughout the West Coast and extended to Minnesota. The April 1998 dust event has impacted the surface aerosol concentration 2-4 times more than any other dust event since 1988. The dust events were observed and interpreted by an ad hoc international web-based virtual community. It would be useful to set up a community-supported web-based infrastructure to monitor the global aerosol pattern for such extreme aerosol events, to alert and to inform the interested communities, and to facilitate collaborative

[Effects of antimicrobial drugs on soil microbial respiration].

Science.gov (United States)

Liu, Feng; Ying, Guang-Guo; Zhou, Qi-Xing; Tao, Ran; Su, Hao-Chang; Li, Xu

2009-05-15

The effects on soil microbial respiration of sulfonamides, tetracyclines, macrolides and so on were studied using the direct absorption method. The results show sulfamethazine, sulfamethoxazole, chlortetracycline, tetracycline, tylosin and trimethoprim inhibit soil respiration 34.33%, 34.43%, 2.71%, 3.08%, 7.13%, 38.08% respectively. Sulfamethoxazole and trimethoprim have the highest inhibition rates among all the antibiotics. In early incubation period (0-2 d), the concentrations above 10 mg x kg(-1) of sulfamethazine, sulfamethoxazole and trimethoprim remarkably decrease soil CO2 emission. The effects of these antibiotics vary with their concentrations too. Sulfamethoxazole and trimethoprim show good dose-response relationships. According to the standard of pesticide safety evaluation protocol, the six antibiotics pose a little risk to soil microbial environment.

From explosions to black lung: a history of efforts to control coal mine dust.

Science.gov (United States)

Weeks, J L

1993-01-01

Highlights in the history of efforts to prevent occupational lung disease among coal miners in the United States are reviewed. The Federal Coal Mine Health and Safety Act of 1969 is summarized, and the sources and effects of its provisions to prevent coal workers' pneumoconiosis are examined. Descriptions follow of the identification of coal workers' pneumoconiosis as a disease, identification of respirable coal mine dust as its cause, and establishment and enforcement of an exposure limit. The development of prevention efforts focusing on surveillance of both exposure and outcome and of enforcement of dust control methods is examined.

Potential human exposure to halogenated flame-retardants in elevated surface dust and floor dust in an academic environment

International Nuclear Information System (INIS)

Allgood, Jaime M.; Jimah, Tamara; McClaskey, Carolyn M.; La Guardia, Mark J.; Hammel, Stephanie C.; Zeineddine, Maryam M.; Tang, Ian W.; Runnerstrom, Miryha G.; Ogunseitan, Oladele A.

2017-01-01

Most households and workplaces all over the world possess furnishings and electronics, all of which contain potentially toxic flame retardant chemicals to prevent fire hazards. Indoor dust is a recognized repository of these types of chemicals including polybrominated diphenyl ethers (PBDEs) and non-polybrominated diphenyl ethers (non-PBDEs). However, no previous U.S. studies have differentiated concentrations from elevated surface dust (ESD) and floor dust (FD) within and across microenvironments. We address this information gap by measuring twenty-two flame-retardant chemicals in dust on elevated surfaces (ESD; n=10) and floors (FD; n=10) from rooms on a California campus that contain various concentrations of electronic products. We hypothesized a difference in chemical concentrations in ESD and FD. Secondarily, we examined whether or not this difference persisted: (a) across the studied microenvironments and (b) in rooms with various concentrations of electronics. A Wilcoxon signed-rank test demonstrated that the ESD was statistically significantly higher than FD for BDE-47 (p=0.01), BDE-99 (p=0.01), BDE-100 (p=0.01), BDE-153 (p=0.02), BDE-154 (p=0.02), and 3 non-PBDEs including EH-TBB (p=0.02), BEH-TEBP (p=0.05), and TDCIPP (p=0.03). These results suggest different levels and kinds of exposures to flame-retardant chemicals for individuals spending time in the sampled locations depending on the position of accumulated dust. Therefore, further research is needed to estimate human exposure to flame retardant chemicals based on how much time and where in the room individuals spend their time. Such sub-location estimates will likely differ from assessments that assume continuous unidimensional exposure, with implications for improved understanding of potential health impacts of flame retardant chemicals. - Highlights: • Brominated flame retardants used in electronic products accumulate in room dust • Various chemical moieties of flame retardants leach

Potential human exposure to halogenated flame-retardants in elevated surface dust and floor dust in an academic environment

Energy Technology Data Exchange (ETDEWEB)

Allgood, Jaime M.; Jimah, Tamara [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States); McClaskey, Carolyn M. [Department of Cognitive Sciences, School of Social Sciences, University of California, Irvine, CA 92697-5100 (United States); La Guardia, Mark J. [Department of Aquatic Health Sciences, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, VA 23062 (United States); Hammel, Stephanie C.; Zeineddine, Maryam M.; Tang, Ian W.; Runnerstrom, Miryha G. [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States); Ogunseitan, Oladele A., E-mail: Oladele.Ogunseitan@uci.edu [Department of Population Health & Disease Prevention, Program in Public Health, University of California, Irvine, CA 92697-3957 (United States)

2017-02-15

Most households and workplaces all over the world possess furnishings and electronics, all of which contain potentially toxic flame retardant chemicals to prevent fire hazards. Indoor dust is a recognized repository of these types of chemicals including polybrominated diphenyl ethers (PBDEs) and non-polybrominated diphenyl ethers (non-PBDEs). However, no previous U.S. studies have differentiated concentrations from elevated surface dust (ESD) and floor dust (FD) within and across microenvironments. We address this information gap by measuring twenty-two flame-retardant chemicals in dust on elevated surfaces (ESD; n=10) and floors (FD; n=10) from rooms on a California campus that contain various concentrations of electronic products. We hypothesized a difference in chemical concentrations in ESD and FD. Secondarily, we examined whether or not this difference persisted: (a) across the studied microenvironments and (b) in rooms with various concentrations of electronics. A Wilcoxon signed-rank test demonstrated that the ESD was statistically significantly higher than FD for BDE-47 (p=0.01), BDE-99 (p=0.01), BDE-100 (p=0.01), BDE-153 (p=0.02), BDE-154 (p=0.02), and 3 non-PBDEs including EH-TBB (p=0.02), BEH-TEBP (p=0.05), and TDCIPP (p=0.03). These results suggest different levels and kinds of exposures to flame-retardant chemicals for individuals spending time in the sampled locations depending on the position of accumulated dust. Therefore, further research is needed to estimate human exposure to flame retardant chemicals based on how much time and where in the room individuals spend their time. Such sub-location estimates will likely differ from assessments that assume continuous unidimensional exposure, with implications for improved understanding of potential health impacts of flame retardant chemicals. - Highlights: • Brominated flame retardants used in electronic products accumulate in room dust • Various chemical moieties of flame retardants leach

Airborne concentrations of metals and total dust during solid catalyst loading and unloading operations at a petroleum refinery.

Science.gov (United States)

Lewis, Ryan C; Gaffney, Shannon H; Le, Matthew H; Unice, Ken M; Paustenbach, Dennis J

2012-09-01

Workers handle catalysts extensively at petroleum refineries throughout the world each year; however, little information is available regarding the airborne concentrations and plausible exposures during this type of work. In this paper, we evaluated the airborne concentrations of 15 metals and total dust generated during solid catalyst loading and unloading operations at one of the largest petroleum refineries in the world using historical industrial hygiene samples collected between 1989 and 2006. The total dust and metals, which included aluminum, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, platinum, silicon, silver, vanadium, and zinc, were evaluated in relation to the handling of four different types of solid catalysts associated with three major types of catalytic processes. Consideration was given to the known components of the solid catalysts and any metals that were likely deposited onto them during use. A total of 180 analytical results were included in this analysis, representing 13 personal and 54 area samples. Of the long-term personal samples, airborne concentrations of metals ranged from refinery and perhaps other modern refineries during the timeframe examined. Copyright © 2011 Elsevier GmbH. All rights reserved.

Lead in Chinese villager house dust: Geographical variation and influencing factors.

Science.gov (United States)

Bi, Xiangyang; Liu, Jinling; Han, Zhixuan; Yang, Wenlin

2015-12-01

House dust has been recognized as an important contributor to Pb exposure of children. Here we conducted a comprehensive study to investigate geographical variation of Pb in Chinese villager house dust. The influences of outdoor soil Pb concentrations, dates of construction, house decoration materials, heating types, and site specific pollution on Pb concentrations in house dust were evaluated. The concentrations of Pb in 477 house dust samples collected from twenty eight areas throughout China varied from 12 to 2510 mg/kg, with a median concentration of 42 mg/kg. The median Pb concentrations in different geographical areas ranged from 16 (Zhangjiakou, Hebei) to 195 mg/kg (Loudi, Hunan). No correlations were found between the house dust Pb concentrations and the age of houses, as well as house decoration materials. Whereas outdoor soil, coal combustion, and site specific pollution may be potential Pb sources. Principal component analysis (PCA) confirmed that elemental compositions of the house dust were controlled by both anthropogenic and geogenic sources. Using scanning electron microscopy (SEM), the Pb bearing particles in the house dust were also studied. Copyright © 2015 Elsevier Ltd. All rights reserved.

Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

Science.gov (United States)

Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

2011-01-01

Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece.

Science.gov (United States)

Besis, Athanasios; Katsoyiannis, Athanasios; Botsaropoulou, Elisavet; Samara, Constantini

2014-05-01

Polybrominated Diphenyl Ethers (PBDEs) are ubiquitous in the indoor environment owing to their use in consumer products and various studies around the world have found higher concentrations indoors than outdoors. Central air conditioner (A/C) systems have been widely used in many workplaces, therefore, studying of PBDEs in central A/C filter dust is useful to better understand the occurrences and health implications of PBDEs in indoor environments. The present study examined the occurrence of PBDEs in central A/C filter dust collected from various workplaces (n = 20) in Thessaloniki, Greece. The sum concentrations of 21 target congeners (∑21PBDE) in A/C dust ranged between 84 and 4062 ng g(-1) with a median value of 1092 ng g(-1), while BDE-209 was found to be the most abundant BDE congener. The daily intake via dust ingestion of PBDEs estimated for the employees of the occupational settings ranged from 3 to 45 ng day(-1) (median 12 ng day(-1)). Copyright © 2014 Elsevier Ltd. All rights reserved.

Determinants, reproducibility, and seasonal variation of ergosterol levels in house dust.

Science.gov (United States)

Leppänen, H K; Nevalainen, A; Vepsäläinen, A; Roponen, M; Täubel, M; Laine, O; Rantakokko, P; von Mutius, E; Pekkanen, J; Hyvärinen, A

2014-06-01

This study aimed to clarify the determinants that affect the concentrations of ergosterol and viable fungi in house dust and to examine the seasonal variation and reproducibility of ergosterol concentrations indoors. In studying the determinants, dust samples from living room floors and vacuum cleaner dust bags were collected from 107 farming and 105 non-farming homes. Ergosterol levels were determined with gas chromatography-mass spectrometry,and the dust bag dust was cultivated for enumeration of fungal genera. Lifestyle and environmental factors, for example using of the fireplace, and visible mold observations in homes, explained 20–26% of the variation of fungal concentrations. For the reproducibility study, samples were collected from five urban homes in four different seasons. The reproducibility of ergosterol determinations within a sample was excellent (ICC = 89.8) for floor dust and moderate (ICC = 63.8) for dust bag dust, but poor when sampling the same home throughout a year (ICC = 31.3 and 12.6, respectively) due to large temporal variation in ergosterol concentrations. In conclusion, environmental characteristics only partially predicted the variation of fungal concentrations. Based on these studies, we recommend repeated sampling of dust over time if one seeks to adequately describe overall fungal levels and exposure in a home. This study shows that levels of ergosterol and viable fungi in house dust are related to visible mold observations. Only 20% of the variation in fungal levels can be explained with questionnaires, and therefore, environmental samples need to be taken in addition. Reproducibility of ergosterol determination was excellent for floor dust, and thus, ergosterol measurements from floor dust samples could be suitable for assessing the fungal load in building investigations. The temporal variation needs to be taken into account when describing the ergosterol concentration of urban homes.

Experimental Method for Measuring Dust Load on Surfaces in Rooms

DEFF Research Database (Denmark)

Lengweiler, Philip; Nielsen, Peter V.; Moser, Alfred

A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms, there is a n......A new experimental setup to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airborne dust concentration considerably. As a basis for developing methods to eliminate dust-related problems in rooms......, there is a need for better understanding of the mechanism of dust deposition and resuspension. With the presented experimental setup, the dust load on surfaces in a channel can be measured as a function of the environmental and surface conditions and the type of particles under controlled laboratory conditions....

Galactic dust and extinction

International Nuclear Information System (INIS)

Lyngaa, G.

1979-01-01

The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards l=50 0 than towards l=230 0 . On the smaller scale, much of the dust responsible for extinction is situated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars. (Auth.)

Organophosphate esters and phthalate esters in human hair from rural and urban areas, Chongqing, China: Concentrations, composition profiles and sources in comparison to street dust.

Science.gov (United States)

He, Ming-Jing; Lu, Jun-Feng; Ma, Jing-Ye; Wang, Huan; Du, Xiao-Fan

2018-06-01

Human hair and street dust from rural and urban areas in Chongqing were collected to analyze Organophosphate esters (OPEs) and phthalate esters (PAEs). Concentrations of OPEs in urban hair were significantly higher than those in rural hair, whereas PAEs concentrations in rural hair were significantly higher than those in urban hair. Different composition patterns of OPEs were observed in rural and urban hair, where tris (2-chloroisopropyl) phosphate (TCIPP), tris (butyl) phosphate (TNBP) and triphenyl phosphate (TPHP) were the dominating analogues in rural hair, accounting for 62.1% of the OPEs burden, and tris (methylphenyl) phosphate (TMPP) exhibited a high contribution in urban hair, responsible for 51.3% of total OPEs, which differed from the composition profiles in corresponding street dust. Analogous composition patterns of PAEs were found in hair of both areas. Di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DNBP), diisobutyl phthalate (DIBP) and diethyl phthalate (DEP) were the most abundant analogues in hair samples, while DEHP was the predominant analogue in dust samples. No clear tendency was obtained between the increasing ages and the concentrations of both compounds. Most OPEs and PAEs congeners showed significantly positive correlation with one another in rural hair. On the contrary, different correlation patterns were observed in urban hair for OPEs and PAEs, indicating multiple or additional sources existed in urban areas. Significant correlations of OPEs and PAEs were found between hair and corresponding street dust samples, but poor correlations of OPEs and PAEs were observed between rural hair and rural indoor dust, suggesting that street dust may be a predominant exogenous source for human exposure to OPEs and PAEs in this area. Copyright © 2018 Elsevier Ltd. All rights reserved.

Untangling the effects of root age and tissue nitrogen on root respiration in Populus tremuloides at different nitrogen supply.

Science.gov (United States)

Ceccon, Christian; Tagliavini, Massimo; Schmitt, Armin Otto; Eissenstat, David M

2016-05-01

Root respiration is a major contributor to terrestrial carbon flux. Many studies have shown root respiration to increase with an increase in root tissue nitrogen (N) concentration across species and study sites. Studies have also shown that both root respiration and root N concentration typically decrease with root age. The effects of added N may directly increase respiration of existing roots or may affect respiration by shifting the age structure of a root population by stimulating growth. To the best of our knowledge, no study has ever examined the effect of added N as a function of root age on root respiration. In this study, root respiration of 13-year-old Populus tremuloides Michx. trees grown in the field and 1-year-old P. tremuloides seedlings grown in containers was analyzed for the relative influence of root age and root N concentration independent of root age on root respiration. Field roots were first tracked using root windows and then sampled at known age. Nitrogen was either applied or not to small patches beneath the windows. In a pot experiment, each plant was grown with its root system split between two separate pots and N was applied at three different levels, either at the same or at different rates between pots. Root N concentration ranged between 1.4 and 1.7% in the field experiment and 1.8 and 2.6% in the seedling experiment. We found that addition of N increased root N concentration of only older roots in the field but of roots of all ages in the potted seedlings. In both experiments, the age-dependent decline in root respiration was largely consistent, and could be explained by a negative power function. Respiration decreased ∼50% by 3 weeks of age. Although root age was the dominant factor affecting respiration in both experiments, in the field experiment, root N also contributed to root respiration independent of root age. These results add further insight into respiratory responses of roots to N addition and mechanisms underlying the

Simulation of the mineral dust content over Western Africa from the event to the annual scale with the CHIMERE-DUST model

Directory of Open Access Journals (Sweden)

C. Schmechtig

2011-07-01

Full Text Available The chemistry and transport model CHIMERE-DUST have been used to simulate the mineral dust cycle over the Sahara in 2006. Surface measurements deployed during the AMMA field campaign allow to test the capability of the model to correctly reproduce the atmospheric dust load and surface concentrations from the daily to the seasonal time-scale. The simulated monthly mean Aerosol Optical Depths (AOD and surface concentrations are significantly correlated with the measured ones. The simulated daily concentrations and hourly AOD are in the same range of magnitude than the observed ones despite relatively high simulated dust emissions. The level of agreement between the simulations and the observations has been quantified at different time scales using statistical parameters classically used to evaluate air quality models. The capability of the model to reproduce the altitude of the dust transport was tested for two contrasted cases of low and high altitude transport. These results highlight the sensitivity of the simulations to the surface winds used as external forcing and the necessity to further constrain the dust mass budget at the regional scale.

Light-enhanced oxygen respiration in benthic phototrophic communities

DEFF Research Database (Denmark)

Epping, EHG; Jørgensen, BB

1996-01-01

Two microelectrode studies demonstrate the effect of Light intensity and photosynthesis on areal oxygen respiration in a hypersaline mat at Guerrero Negro, Mexico, and in an intertidal sediment at Texel, The Netherlands. The hypersaline mat was studied in the laboratory at light intensities of 0...... the day at prevailing light intensities. A 1-dimensional diffusion-reaction model was used to estimate gross photosynthesis and oxygen respiration per volume of sediment, as well as the euphotic depth and the sediment-water interface concentration of oxygen. Areal gross photosynthesis ranged from 9...

Emphysema and pulmonary impairment in coal miners: Quantitative relationship with dust exposure and cigarette smoking

International Nuclear Information System (INIS)

Kuempel, E D; Vallyathan, V; Green, F H Y

2009-01-01

Coal miners have been shown to be at increased risk of developing chronic obstructive pulmonary diseases including emphysema. The objective of this study was to determine whether lifetime cumulative exposure to respirable coal mine dust is a significant predictor of developing emphysema at a clinically-relevant level of severity by the end of life, after controlling for cigarette smoking and other covariates. Clinically-relevant emphysema severity was determined from the association between individuals' lung function during life (forced expiratory volume in one second, FEV 1 , as a percentage of predicted normal values) and emphysema severity at autopsy (as the proportion of lung tissue affected). In a logistic regression model, cumulative exposure to respirable coal mine dust was a statistically significant predictor of developing clinically-relevant emphysema severity, among both ever-smokers and never-smokers. The odds ratio for developing emphysema associated with FEV 1 3 x yr) was 2.30 (1.46-3.64, 95% confidence limits), and at the cohort mean cigarette smoking (among smokers: 42 pack-years) was 1.95 (1.39-2.79).

Miniaturized test system for soil respiration induced by volatile pollutants

International Nuclear Information System (INIS)

Kaufmann, Karin; Chapman, Stephen J.; Campbell, Colin D.; Harms, Hauke; Hoehener, Patrick

2006-01-01

A miniaturized method based on 96-well microtitre plates was developed and used to study respiration in pristine and contaminated soils following addition of volatile substrates. Small soil samples were exposed to fuel components, which were volatilized from spatially separate reservoirs of 2,2,4,4,6,8,8-heptamethylnonane (HMN) as an organic carrier. Respiration was determined as CO 2 production by means of a pH-indicator and bicarbonate-containing agar, or as 14 CO 2 evolution from 14 C-labelled substrates. Substrate concentrations inducing maximum microbial activity or inhibition were determined and CO 2 production profiles examined by multivariate analysis. When high concentrations of fuel components were applied, distinction of hydrocarbon exposed soils from unexposed soil was achieved within 6 h of incubation. With low concentrations, adequate distinction was achieved after 24 h, probably as a result of community adaptation. Nutrient limitation was identified with the 14 C method for toluene, and the optimal N and P amendment determined. Further potential applications of this rapid and inexpensive method are outlined. - A new method to study soil respiration is used when volatile organic contaminants are added

Effects of uniformities of deposition of respirable particles on filters on determining their quartz contents by using the direct on-filter X-ray diffraction (DOF XRD) method

International Nuclear Information System (INIS)

Chen, Ching-Hwa; Tsaia, Perng-Jy; Lai, Chane-Yu; Peng, Ya-Lian; Soo, Jhy-Charm; Chen, Cheng-Yao; Shih, Tung-Sheng

2010-01-01

In this study, field samplings were conducted in three workplaces of a foundry plant, including the molding, demolding, and bead blasting, respectively. Three respirable aerosol samplers (including a 25-mm aluminum cyclone, nylon cyclone, and IOSH cyclone) were used side-by-side to collect samples from each selected workplace. For each collected sample, the uniformity of the deposition of respirable dusts on the filter was measured and its free silica content was determined by both the DOF XRD method and NIOSH 7500 XRD method (i.e., the reference method). A same trend in measured uniformities can be found in all selected workplaces: 25-mm aluminum cyclone > nylon cyclone > IOSH cyclone. Even for samples collected by the sampler with the highest uniformity (i.e., 25-mm aluminum cyclone), the use of the DOF XRD method would lead to the measured free silica concentrations 1.15-2.89 times in magnitude higher than that of the reference method. A new filter holder should be developed with the minimum uniformity comparable to that of NIOSH 7500 XRD method (=0.78) in the future. The use of conversion factors for correcting quartz concentrations obtained from the DOF XRD method based on the measured uniformities could be suitable for the foundry industry at this stage.

Saharan dust levels in Greece and received inhalation doses

Directory of Open Access Journals (Sweden)

C. Mitsakou

2008-12-01

Full Text Available The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×10⁸ tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in the south European Region and especially in urban areas, where there is also significant contribution from anthropogenic sources. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM₁₀ concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM₁₀ concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by more than 20% to the annual number of exceedances – PM₁₀ values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

Energy Technology Data Exchange (ETDEWEB)

Vakylabad, Ali Behrad, E-mail: alibehzad86@yahoo.co.uk [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Engineers of Nano and Bio Advanced Sciences Company (ENBASCo.), ATIC, Mohaghegh University (Iran, Islamic Republic of); Schaffie, Mahin [Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ranjbar, Mohammad [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Manafi, Zahra [Sarcheshmeh Copper Complex, National Iranian Copper Industry Company (Iran, Islamic Republic of); Darezereshki, Esmaeel [Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Energy and Environmental Engineering Research Center (EERC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

2012-11-30

Highlights: Black-Right-Pointing-Pointer Flotation concentrate and smelter dust were sampled and combined. Black-Right-Pointing-Pointer Copper bioleaching from the combined was investigated. Black-Right-Pointing-Pointer Two bio-reactors were investigated and optimized: stirred and airlift. Black-Right-Pointing-Pointer STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu{sub 2}S, CuS, and Cu{sub 5}FeS{sub 4}.Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

International Nuclear Information System (INIS)

Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

2012-01-01

Highlights: ► Flotation concentrate and smelter dust were sampled and combined. ► Copper bioleaching from the combined was investigated. ► Two bio-reactors were investigated and optimized: stirred and airlift. ► STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu 2 S, CuS, and Cu 5 FeS 4 .Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

Exposure to grain dust in Great Britain.

Science.gov (United States)

Spankie, Sally; Cherrie, John W

2012-01-01

Airborne grain dust is a complex mixture of fragments of organic material from grain, plus mineral matter from soil, and possible insect, fungal, or bacterial contamination or their toxic products, such as endotoxin. In the 1990s, grain workers in Britain were frequently exposed to inhalable dust >10 mg.m(-3) (8 h), with particularly high exposures being found at terminals where grain was imported or exported and in drying operations (personal exposure typically approximately 20 mg.m(-3)). Since then, the industry has made substantial progress in improving the control of airborne dust through better-designed processes, increased automation, and an improved focus on product quality. We have used information from the published scientific literature and a small survey of industry representatives to estimate current exposure levels. These data suggest that current long-term exposure to inhalable dust for most workers is on average less than approximately 3 mg.m(-3), with perhaps 15-20% of individual personal exposures being >10 mg.m(-3). There are no published data from Britain on short-term exposure during cleaning and other tasks. We have estimated average levels for a range of tasks and judge that the highest levels, for example during some cleaning activities and certain process tasks such as loading and packing, are probably approximately10 mg.m(-3). Endotoxin levels were judged likely to be dust levels are <10 mg.m(-3). There are no published exposure data on mycotoxin, respirable crystalline silica, and mite contamination but these are not considered to present widespread problems in the British industry. Further research should be carried out to confirm these findings.

Characteristics of mineral dust impacting the Persian Gulf

Science.gov (United States)

Ahmady-Birgani, Hesam; McQueen, Kenneth G.; Mirnejad, Hassan

2018-02-01

It is generally assumed that severe dust events in western Iran could be responsible for elevated levels of toxic and radioactive elements in the region. Over a period of 5 months, from January 2012 to May 2012, dust particles in the size range PM10 (i.e. chemical compositions of dust and aerosol samples collected during the non-dusty periods and during two severe dust events. Results of ICP-MS analysis of components indicate that during dust events the concentrations of major elements such as Ca, Mg, Al and K increase relative to ambient conditions when Fe and trace elements such as Cu, Cr, Ni, Pb and Zn are in higher proportions. Toxic trace elements that are generally ascribed to human activities, including industrial and urban pollution, are thus proportionately more abundant in the dust under calm conditions than during dust events, when their concentration is diluted by more abundant mineral particles of quartz, calcite and clay. The variability of chemical species during two dust events, noted by tracking the dust plumes in satellite images, was also assessed and the results relate to two different source areas, namely northern Iraq and northwestern Syria.

Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica.

Science.gov (United States)

Jia, Shuxia; McLaughlin, Neil B; Gu, Jiacun; Li, Xingpeng; Wang, Zhengquan

2013-06-01

Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the

Can we relate respiration rates of bark and wood with tissue nitrogen concentrations and branch-level CO2 fluxes across woody species?

Science.gov (United States)

Eller, A. S.; Wright, I.; Cernusak, L. A.

2013-12-01

Respiration from above-ground woody tissue is generally responsible for 5-15% of ecosystem respiration (~ 30% of total above-ground respiration). The CO2 respired by branches comes from both the sapwood and the living layers within the bark, but because there is considerable movement of respired CO2 within woody tissues (e.g. in the transpiration stream), and because the bark can present a considerable barrier to CO2 diffusion, it can be difficult to interpret measured CO2 efflux from intact branches in relation to the respiration rates of the component tissues, and to relative mass allocation to each. In this study we investigated these issues in 15 evergreen tree and shrub species native to the Sydney area in eastern Australia. We measured CO2 efflux and light-dependent refixation of respired CO2 in photosynthetic bark from the exterior surfaces of branches (0.5-1.5 cm in diameter), and measured the tissue-specific respiration rates of the bark and wood from those same branches. We also measured the nitrogen content and tissue density of the wood and bark to determine: 1) Among species, what is the relationship between %N and tissue respiration? 2) How is photosynthetic refixation of CO2 related to respiration and %N in the bark and underlying wood? and 3) What is the relationship between branch CO2 efflux and the respiration rates of the underlying wood and bark that make up the branch? Across the 15 species %N was a better predictor of respiration in wood than in bark. CO2 efflux measured from the exterior of the stem in the dark was positively correlated with photosynthetic refixation and explained ~40% of the variation in rates of refixation. Refixation rates were not strongly related to bark or wood %N. Differences among species in CO2 efflux rates were not well explained by differences in bark or wood %N and there was a stronger relationship between bark respiration and CO2 efflux than between wood respiration and CO2 efflux. These results suggest that the

Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

Science.gov (United States)

Mamali, Dimitra; Marinou, Eleni; Sciare, Jean; Pikridas, Michael; Kokkalis, Panagiotis; Kottas, Michael; Binietoglou, Ioannis; Tsekeri, Alexandra; Keleshis, Christos; Engelmann, Ronny; Baars, Holger; Ansmann, Albert; Amiridis, Vassilis; Russchenberg, Herman; Biskos, George

2018-05-01

In situ measurements using unmanned aerial vehicles (UAVs) and remote sensing observations can independently provide dense vertically resolved measurements of atmospheric aerosols, information which is strongly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse mode (i.e. particles having radii > 0.5 µm), where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.

Pulmonary function, respiratory symptoms, and dust exposures among workers engaged in early manufacturing processes of tea: a cohort study.

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Shieh, Tzong-Shiun; Chung, Jui-Jung; Wang, Chung-Jing; Tsai, Perng-Jy; Kuo, Yau-Chang; Guo, How-Ran

2012-02-13

To evaluate pulmonary function and respiratory symptoms in workers engaged in the early manufacturing processes of tea and to identify the associated factors, we conducted a study in a tea production area in Taiwan. We recruited tea workers who engaged in the early manufacturing process in the Mountain Ali area in Taiwan and a comparison group of local office workers who were matched for age, gender, and smoking habits. We performed questionnaire interviews, pulmonary function tests, skin prick tests, and measurement of specific IgE for tea on the participants and assessed tea dust exposures in the tea factories. The 91 participating tea workers had higher prevalence of respiratory symptoms than the comparison group (32 participants). Among tea workers, ball-rolling workers had the highest prevalence of symptoms and the highest exposures of inhalable dusts. At baseline, tea workers had similar pulmonary functions as the comparison group, but compared to the other tea workers ball-rolling workers had a lower ratio of the 1-second forced expiratory volume to forced vital capacity (FEV1/FVC) and a lower maximal mid-expiratory flow rate expressed as% of the predicted value--MMF (%pred). A total of 58 tea workers participated in the on-site investigation and the cross-shift lung function measurements. We found ball-rolling yielded the highest inhalable dust level, panning yielded the highest respirable dust level, and withering yielded the lowest levels of both dusts. Ball-rolling also yielded the highest coarse fraction (defined as inhalable dusts minus respirable dusts), which represented exposures from nose to tracheobronchial tract. During the shift, we observed significant declines in pulmonary function, especially in ball-rolling workers. Multiple regressions showed that age, height, work tasks, coarse fraction, and number of months working in tea manufacturing each year were independent predictors of certain pulmonary function parameters in tea workers. Tea

Investigating A Novel Flame Retardant Known as V6: Measurements in Baby Products, House Dust and Car Dust

Science.gov (United States)

Fang, Mingliang; Webster, Thomas F.; Gooden, David; Cooper, Ellen M.; McClean, Michael D.; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M.

2013-01-01

With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors’ knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected, and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (> 98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using Accelerated Solvent Extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6 % of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than the house dust, potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and TCEP in the dust samples, suggesting that the use of V6 is a significant source of TCEP

Air Pollution Modelling to Predict Maximum Ground Level Concentration for Dust from a Palm Oil Mill Stack

Directory of Open Access Journals (Sweden)

Regina A. A.

2010-12-01

Full Text Available The study is to model emission from a stack to estimate ground level concentration from a palm oil mill. The case study is a mill located in Kuala Langat, Selangor. Emission source is from boilers stacks. The exercise determines the estimate the ground level concentrations for dust to the surrounding areas through the utilization of modelling software. The surround area is relatively flat, an industrial area surrounded by factories and with palm oil plantations in the outskirts. The model utilized in the study was to gauge the worst-case scenario. Ambient air concentrations were garnered calculate the increase to localized conditions. Keywords: emission, modelling, palm oil mill, particulate, POME

Concentration of the genera Aspergillus, Eurotium and Penicillium in 63-μm house dust fraction as a method to predict hidden moisture damage in homes

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Assadian Ojan

2009-07-01

Full Text Available Abstract Background Quantitative measurements of mould enrichment of indoor air or house dust might be suitable surrogates to evaluate present but hidden moisture damage. Our intent was to develop a house-dust monitoring method to detect hidden moisture damage excluding the influence of outdoor air, accumulated old dust, and dust swirled up from room surfaces. Methods Based on standardized measurement of mould spores in the 63-μm fraction of house dust yielded by carpets, the background concentrations were determined and compared to simultaneously obtained colony numbers and total spore numbers of the indoor air in 80 non-mouldy living areas during summer and winter periods. Additionally, sampling with a vacuum-cleaner or manual sieve was compared to sampling with a filter holder or sieving machine, and the evaluative power of an established two-step assessment model (lower and upper limits was compared to that of a one-step model (one limit in order to derive concentration limits for mould load in house dust. Results Comparison with existing evaluation procedures proved the developed method to be the most reliable means of evaluating hidden moisture damage, yielding the lowest false-positive results (specificity 98.7%. Background measurements and measurements in 14 mouldy rooms show that even by evaluating just the indicator genera in summer and winter, a relatively certain assessment of mould infestation is possible. Conclusion A one-step evaluation is finally possible for house dust. The house-dust evaluation method is based on analysis of the indicator genera Aspergillus, Eurotium and Penicillium spp., which depend on the total fungal count. Inclusion of further moisture indicators currently appears questionable, because of outdoor air influence and the paucity of measurements.

Ground level and Lidar monitoring of volcanic dust and dust from Patagonia

Science.gov (United States)

Otero, L. A.; Losno, R.; Salvador, J. O.; Journet, E.; Qu, Z.; Triquet, S.; Monna, F.; Balkanski, Y.; Bulnes, D.; Ristori, P. R.; Quel, E. J.

2013-05-01

A combined approach including ground level aerosol sampling, lidar and sunphotometer measurements is used to monitor suspended particles in the atmosphere at several sites in Patagonia. Motivated by the Puyehue volcanic eruption in June 2011 two aerosol monitoring stations with several passive and active instruments were installed in Bariloche and Comodoro Rivadavia. The main goal which is to monitor ground lifted and transported ashes and dust involving danger to civil aviation, is achieved by measuring continuously aerosol concentration at ground level and aerosol vertical distribution using lidar. In addition, starting from December 2011, continuous series of weekly accumulated aerosol concentrations at Rio Gallegos are being measured to study the impact of Patagonian dust over the open ocean on phytoplankton primary productivity and CO2 removal. These measurements are going to be coupled with LIDAR monitoring and a dust optical response models to test if aerosol extrapolation can be done from the ground to the top of the layer. Laboratory chemical analysis of the aerosols will include elemental composition, solubilisation kinetic and mineralogical determination. Expected deliverables for this study is the estimation of the amount of dust exported from Patagonia towards the South Atlantic, its chemical properties, including bioavailability simulation, from model and comparison to experimental measurements.

The real limits to marine life: a further critique of the Respiration Index

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Seibel, B. A.; Childress, J. J.

2013-05-01

The recently proposed "Respiration Index" (RI = log PO2/PCO2) suggests that aerobic metabolism is limited by the ratio of reactants (oxygen) to products (carbon dioxide) according to the thermodynamics of cellular respiration. Here, we demonstrate further that, because of the large standard free energy change for organic carbon oxidation (ΔG° = -686 kcal mol-1), carbon dioxide can never reach concentrations that would limit the thermodynamics of this reaction. A PCO2 to PO2 ratio of 10503 would be required to reach equilibrium (equilibrium constant, Keq = 10503), where ΔG = 0. Thus, a Respiration Index of -503 would be the real thermodynamic limit to aerobic life. Such a Respiration Index is never reached, either in the cell or in the environment. Moreover, cellular respiration and oxygen provision are kinetically controlled such that, within limits, environmental oxygen and CO2 concentrations have little to do with intracellular concentrations. The RI is fundamentally different from the aragonite saturation state, a thermodynamic index used to quantify the potential effect of CO2 on calcification rates, because of its failure to incorporate the equilibrium constant of the reaction. Not only is the RI invalid, but its use leads to incorrect and misleading predictions of the threat of changing oxygen and carbon dioxide to marine life. We provide a physiological framework that identifies oxygen thresholds and allows for synergistic effects of ocean acidification and global warming.

The real limits to marine life: a further critique of the Respiration Index

Directory of Open Access Journals (Sweden)

B. A. Seibel

2013-05-01

Full Text Available The recently proposed "Respiration Index" (RI = log PO2/PCO2 suggests that aerobic metabolism is limited by the ratio of reactants (oxygen to products (carbon dioxide according to the thermodynamics of cellular respiration. Here, we demonstrate further that, because of the large standard free energy change for organic carbon oxidation (ΔG° = −686 kcal mol−1, carbon dioxide can never reach concentrations that would limit the thermodynamics of this reaction. A PCO2 to PO2 ratio of 10503 would be required to reach equilibrium (equilibrium constant, Keq = 10503, where ΔG = 0. Thus, a Respiration Index of −503 would be the real thermodynamic limit to aerobic life. Such a Respiration Index is never reached, either in the cell or in the environment. Moreover, cellular respiration and oxygen provision are kinetically controlled such that, within limits, environmental oxygen and CO2 concentrations have little to do with intracellular concentrations. The RI is fundamentally different from the aragonite saturation state, a thermodynamic index used to quantify the potential effect of CO2 on calcification rates, because of its failure to incorporate the equilibrium constant of the reaction. Not only is the RI invalid, but its use leads to incorrect and misleading predictions of the threat of changing oxygen and carbon dioxide to marine life. We provide a physiological framework that identifies oxygen thresholds and allows for synergistic effects of ocean acidification and global warming.

Stimulation of mitochondrial respiration induced by laser irradiation in the presence of rhodamine dyes

International Nuclear Information System (INIS)

Krasnikov, B.F.; Zorov, D.B.

1996-01-01

The effect of micromolar concentration of rhodamine 123 (methylrhodamine) and ethyl and amyl esters of unsubstituted rhodamine on oxygen consumption by rat liver mitochondria was studied under irradiation by an argon laser (488 and 514 nm). Irradiation of mitochondria in the presence of rhodamine stimulates their respiration. Light-induced stimulation of respiration is not inhibited by free radical scavenger ionol and by inhibitor of the permeability transition pore cyclosporine A. Stimulation of respiration by moderate doses of radiation is reversed in the dark. Increase in radiation dose resulted in only partial reversal of stimulated respiration in the dark. Rhodamine efficacy in stimulation of mitochondrial respiration depends on its structure (amyl > ethyl > methylrhodamine). 22 refs.; 4 figs

Determinants of manganese levels in house dust samples from the CHAMACOS cohort

Energy Technology Data Exchange (ETDEWEB)

Gunier, R.B., E-mail: gunier@berkeley.edu [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States); Jerrett, M. [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States); Smith, D.R.; Jursa, T. [Microbiology and Environmental Toxicology, University of California, Santa Cruz, CA (United States); Yousefi, P.; Camacho, J.; Hubbard, A.; Eskenazi, B.; Bradman, A. [Center for Environmental Research and Children’s Health (CERCH), School of Public Health, University of California, Berkeley, CA (United States)

2014-11-01

Introduction: Manganese (Mn) is an essential nutrient, but at high exposure levels Mn is a neurotoxicant. The fungicides maneb and mancozeb are approximately 21% Mn by weight and more than 150,000 kg are applied each year to crops in the Salinas Valley, California. It is not clear, however, whether agricultural use of these fungicides increases Mn levels in homes. Materials and methods: We collected house dust samples from 378 residences enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study with a second sample collected approximately nine months later from 90 of the residences. House dust samples were analyzed for Mn using inductively coupled plasma optical emission spectroscopy. Information from interviews, home inspections, and pesticide use reports was used to identify potential predictors of Mn dust concentrations and loadings. Results: Mn was detectable in all dust samples. The median Mn concentration was 171 μg/g and median Mn loading was 1,910 μg/m{sup 2} at first visit. In multivariable models, Mn dust concentrations and loadings increased with the number of farmworkers in the home and the amount of agricultural Mn fungicides applied within three kilometers of the residence during the month prior to dust sample collection. Dust concentrations of Mn and other metals (lead, cadmium and chromium) were higher in residences located in the southern Salinas Valley compared those located in other areas of the Salinas Valley. Dust loadings of Mn and other metals were also higher in residences located on Antioch Loam soil than other soil types, and in homes with poor or average housekeeping practices. Conclusions: Agricultural use of Mn containing fungicides was associated with Mn dust concentrations and loadings in nearby residences and farmworker homes. Housekeeping practices and soil type at residence were also important factors related to dust metal concentrations and loadings. - Highlights: • Manganese dust

'Nuisance Dust' - a Case for Recalibration?

Science.gov (United States)

Datson, Hugh; Marker, Brian

2013-04-01

This paper considers the case for a review and recalibration of limit values and acceptability criteria for 'nuisance dust', a widely encountered but poorly defined and regulated aspect of particulate matter pollution. Specific dust fractions such as PM10 and asbestiforms are well characterised and have limit values enshrined in legislation. National, and international, limit values for acceptable concentrations of PM10 and other fractions of particulate matter have been defined and agreed. In the United Kingdom (UK), these apply to both public and workplace exposures. By contrast, there is no standard definition or universal criteria against which acceptable levels for 'nuisance dust' can be assessed. This has implications for land-use planning and resource utilisation. Without meaningful limit values, inappropriate development might take place too near to residential dwellings or land containing economically important mineral resources may be effectively sterilised. Furthermore, the expression 'nuisance dust' is unhelpful in that 'nuisance' has a specific meaning in environmental law whilst 'nuisance dust' is often taken to mean 'generally visible particulate matter'. As such, it is associated with the social and broader environmental impacts of particulate matter. PM10 concentrations are usually expressed as a mass concentration over time. These can be determined using a range of techniques. While results from different instruments are generally comparable, data obtained from alternative methods for measuring 'nuisance dust' are rarely interchangeable. In the UK, many of the methods typically used are derived from approaches developed under the HMIP (Her Majesty's Inspectorate of Pollution) regime in the 1960s onwards. Typical methods for 'nuisance dust' sampling focus on measurement of dust mass (from the weight of dust collected in an open container over time) or dust soiling (from loss of reflectance and or obscuration of a surface discoloured by dust over

Effect of nitrogen on the seasonal course of growth and maintenance respiration in stems of Norway spruce trees.

Science.gov (United States)

Stockfors, Jan; Linder, Sune

1998-03-01

To determine effects of stem nitrogen concentration ([N]) on the seasonal course of respiration, rates of stem respiration of ten control and ten irrigated-fertilized (IL), 30-year-old Norway spruce trees (Picea abies (L.) Karst.), growing in northern Sweden, were measured on seven occasions from June 1993 to April 1994. To explore sources of seasonal variation and mechanisms of fertilization effects on respiration, we separated total respiration into growth and maintenance respiration for both xylem and phloem bark. Stem respiration increased in response to the IL treatment and was positively correlated with growth rate, volume of living cells and stem nitrogen content. However, no significant effect of IL treatment or [N] in the living cells was found for respiration per unit volume of live cells. Total stem respiration during the growing season (June to September) was estimated to be 16.7 and 29.7 mol CO(2) m(-2) for control and IL-treated trees, respectively. Respiration during the growing season accounted for approximately 64% of total annual respiration. Depending on the method, estimated growth respiration varied between 40 and 60% of total respiration during the growing season. Between 75 and 80% of the live cell volume in the stems was in the phloem, and phloem maintenance accounted for about 70% of maintenance respiration. Because most of the living cells were found in the phloem, and the living xylem cells were concentrated in the outer growth rings, we concluded that the best base for expressing rates of stem growth and maintenance respiration in young Norway spruce trees is stem surface area.

Workplace field testing of the pressure drop of particulate respirators using welding fumes.

Science.gov (United States)

Cho, Hyun-Woo; Yoon, Chung-Sik

2012-10-01

In a previous study, we concluded that respirator testing with a sodium chloride aerosol gave a conservative estimate of filter penetration for welding fume aerosols. A rapid increase in the pressure drop (PD) of some respirators was observed as fumes accumulated on the filters. The present study evaluated particulate respirator PD based on workplace field tests. A field PD tester was designed and validated using the TSI 8130 Automatic Filter Tester, designed in compliance with National Institute for Occupational and Safety and Health regulation 42 CFR part 84. Three models (two replaceable dual-type filters and one replaceable single-type filter) were evaluated against CO(2) gas arc welding on mild steel in confined booths in the workplace. Field tests were performed under four airborne concentrations (27.5, 15.4, 7.9, and 2.1 mg m(-3)). The mass concentration was measured by the gravimetric method, and number concentration was monitored using P-Trak (Model 8525, TSI, USA). Additionally, photos and scanning electron microscopy-energy dispersive X-ray spectroscopy were used to visualize and analyze the composition of welding fumes trapped in the filters. The field PD tester showed no significant difference compared with the TSI tester. There was no significant difference in the initial PD between laboratory and field results. The PD increased as a function of fume load on the respirator filters for all tested models. The increasing PD trend differed by models, and PD increased rapidly at high concentrations because greater amount of fumes accumulated on the filters in a given time. The increase in PD as a function of fume load on the filters showed a similar pattern as fume load varied for a particular model, but different patterns were observed for different models. Images and elemental analyses of fumes trapped on the respirator filters showed that most welding fumes were trapped within the first layer, outer web cover, and second layer, in order, while no fumes

Seasonal and occupational trends of five organophosphate pesticides in house dust.

Science.gov (United States)

Smith, Marissa N; Workman, Tomomi; McDonald, Katie M; Vredevoogd, Melinda A; Vigoren, Eric M; Griffith, William C; Thompson, Beti; Coronado, Gloria D; Barr, Dana; Faustman, Elaine M

2017-07-01

Since 1998, the University of Washington's Center for Child Environmental Health Risks Research has followed a community-based participatory research strategy in the Lower Yakima Valley of Washington State to assess pesticide exposure among families of Hispanic farmworkers. As a part of this longitudinal study, house dust samples were collected from both farmworker and non-farmworker households, across three agricultural seasons (thinning, harvest and non-spray). The household dust samples were analyzed for five organophosphate pesticides: azinphos-methyl, phosmet, malathion, diazinon, and chlorpyrifos. Organophosphate pesticide levels in house dust were generally reflective of annual use rates and varied by occupational status and agricultural season. Overall, organophosphate pesticide concentrations were higher in the thinning and harvest seasons than in the non-spray season. Azinphos-methyl was found in the highest concentrations across all seasons and occupations. Farmworker house dust had between 5- and 9-fold higher concentrations of azinphos-methyl than non-farmworker house dust. Phosmet was found in 5-7-fold higher concentrations in farmworker house dust relative to non-farmworker house dust. Malathion and chlorpyriphos concentrations in farmworker house dust ranged between 1.8- and 9.8-fold higher than non-farmworker house dust. Diazinon showed a defined seasonal pattern that peaked in the harvest season and did not significantly differ between farmworker and non-farmworker house dust. The observed occupational differences in four out of five of the pesticide residues measured provides evidence supporting an occupational take home pathway, in which workers may bring pesticides home on their skin or clothing. Further, these results demonstrate the ability of dust samples to inform the episodic nature of organophosphate pesticide exposures and the need to collect multiple samples for complete characterization of exposure potential.

Respirator studies for the National Institute for Occupational Safety and Health. Progress report, July 1, 1974--June 30, 1975

International Nuclear Information System (INIS)

Douglas, D.D.; Revoir, W.; Lowry, P.L.

1976-08-01

Respirator studies carried out in FY 1975 for the National Institute for Occupational Safety and Health were concentrated in two major areas: (1) the development of respirator test equipment and methods to improve the means of evaluating the performance of respirators, (2) the testing of respirators to obtain quantitative data to permit recommendations to be made to upgrade respirator performance criteria. Major accomplishments included obtaining man-test results on several different respirators using an anthropometrically selected test panel, determination of respirator exhalation valve leakages under static and dynamic conditions, and determination of the effects of respirator strap tension on facepiece leakage

Radioisotope dust pollution monitor

International Nuclear Information System (INIS)

Szepke, R.; Harasimczuk, J.; Dobrowiecki, J.

1990-01-01

Measuring principles and specification of two dust monitors: station-type AMIZ and portable-type PIK-10 for ambient air pollution are presented. The first one, a fully automatic instrument is destined for permanent monitoring of air pollution in preset sampling time from .25 to 24 hours. The second one was developed as a portable working model. Both instruments display their results in digital form in dust concentration units. (author)

[Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

Science.gov (United States)

Lu, Xing-li; Liao, Yun-cheng

2015-06-01

To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

Microbial respiration per unit microbial biomass increases with carbon-to-nutrient ratios in soils

Science.gov (United States)

Spohn, Marie; Chodak, Marcin

2015-04-01

The ratio of carbon-to-nutrient in forest floors is usually much higher than the ratio of carbon-to-nutrient that soil microorganisms require for their nutrition. In order to understand how this mismatch affects carbon cycling, the respiration rate per unit soil microbial biomass carbon - the metabolic quotient (qCO2) - was studied. This was done in a field study (Spohn and Chodak, 2015) and in a meta-analysis of published data (Spohn, 2014). Cores of beech, spruce, and mixed spruce-beech forest soils were cut into slices of 1 cm from the top of the litter layer down to 5 cm in the mineral soil, and the relationship between the qCO2 and the soil carbon-to-nitrogen (C:N) and the soil carbon-to-phosphorus (C:P) ratio was analyzed. We found that the qCO2 was positively correlated with soil C:N ratio in spruce soils (R = 0.72), and with the soil C:P ratio in beech (R = 0.93), spruce (R = 0.80) and mixed forest soils (R = 0.96). We also observed a close correlation between the qCO2 and the soil C concentration in all three forest types. Yet, the qCO2 decreased less with depth than the C concentration in all three forest types, suggesting that the change in qCO2 is not only controlled by the soil C concentration. We conclude that microorganisms increase their respiration rate per unit biomass with increasing soil C:P ratio and C concentration, which adjusts the substrate to their nutritional demands in terms of stoichiometry. In an analysis of literature data, I tested the effect of the C:N ratio of soil litter layers on microbial respiration in absolute terms and per unit microbial biomass C. For this purpose, a global dataset on the microbial respiration rate per unit microbial biomass C - termed the metabolic quotient (qCO2) - was compiled form literature data. It was found that the qCO2 in the soil litter layers was positively correlated with the litter C:N ratio and negatively related with the litter nitrogen (N) concentration. The positive relation between the qCO2

Aerosol-ozone correlations during dust transport episodes

Directory of Open Access Journals (Sweden)

P. Bonasoni

2004-01-01

Full Text Available Its location in the Mediterranean region and its physical characteristics render Mt. Cimone (44°11′ N, 10°42′ E, the highest peak of the Italian northern Apennines (2165 m asl, particularly suitable to study the transport of air masses from the north African desert area to Europe. During these northward transports 12 dust events were registered in measurements of the aerosol concentration at the station during the period June–December 2000, allowing the study of the impact of mineral dust transports on free tropospheric ozone concentrations, which were also measured at Mt. Cimone. Three-dimensional backward trajectories were used to determine the air mass origin, while TOMS Aerosol Index data for the Mt. Cimone area were used to confirm the presence of absorbing aerosol over the measurement site. A trajectory statistical analysis allowed identifying the main source areas of ozone and aerosols. The analysis of these back trajectories showed that central Europe and north and central Italy are the major pollution source areas for ozone and fine aerosol, whereas the north African desert regions were the most important source areas for coarse aerosol and low ozone concentrations. During dust events, the Mt. Cimone mean volume concentration for coarse particles was 6.18 µm3/cm3 compared to 0.63 µm3/cm3 in dust-free conditions, while the ozone concentrations were 4% to 21% lower than the monthly mean background values. Our observations show that surface ozone concentrations were lower than the background values in air masses coming from north Africa, and when these air masses were also rich in coarse particles, the lowest ozone values were registered. Moreover, preliminary results on the possible impact of the dust events on PM10 and ozone values measured in Italian urban and rural areas showed that during the greater number of the considered dust events, significant PM10 increases and ozone decreases have occurred in the Po valley.

[The epidemiological validation of the MPEL for grain dust in the atmosphere].

Science.gov (United States)

Pinigin, M A; Cherepov, E M; Safiulin, A A; Petrova, I V; Mukhambetova, L Kh; Osipova, E M; Veselov, A P

1998-01-01

The use of calculating and gravimetric methods for examining the grain dust pollution of the ambient air at the site of an elevator determined the maximum single, mean daily, and mean annual concentrations at different distances from the source of dust emission. The mean ratio of these concentrations was 12.1:4.3:1, respectively. The calculated concentration-effect and concentration-time relationships provided evidence for the maximum single, mean daily, and mean annual allowable concentrations for grain dust in the ambient air.

Exposure assessment of lead from food and airborne dusts and biomonitoring in pregnant mothers, their fetus and siblings in Karachi, Pakistan and Shimotsuke, Japan.

Science.gov (United States)

Kayama, Fujio; Fatmi, Zafar; Ikegami, Akihiko; Mizuno, Atsuko; Ohtsu, Mayumi; Mise, Nathern; Cui, Xiaoyi; Ogawa, Masanori; Sakamoto, Takako; Nakagi, Yoshiko; Yoshida, Takahiko; Sahito, Ambreen; Naeem, Shahla; Ghias, Kulsoom; Zuberi, Hina; Tariq, Kanwal; Kobayashi, Yayoi; Nohara, Keiko

2016-03-01

Exposure assessment of lead (Pb) and Arsenic (As) from food, water, and house dust intake were assessed among pregnant women, their children and fetuses in Pakistan and Japan, as well as their body burden of the metals in their blood. Fifty families which included a pregnant woman, a fetus and the 1-3-year-old siblings were recruited in Karachi and Khairpur in Pakistan, and Shimotsuke and Asahikawa in Japan, respectively. Their dietary exposure to Pb and As was measured in 3-day food duplicates and drinking water by ICP-MP. Pb in house dust and respirable dust was evaluated with an energy dispersive X-ray fluorescence spectrometry. Non-radioactive isotope Pb profiles of blood specimens will be compared with those of the exposure origins, such as food duplicates, respirable house dust, the soils nearby, and gasoline. Judging from the data collected and analyzed so far, contribution from dietary intake is highly correlated to higher body burden of Pb among Pakistani mothers. Additional data analyses will reveal the status of Pb and As body burden in Pakistani mothers, fetuses and their siblings, and causal sources of high body burden is delineated by Pb isotope profile analysis of different sources of Pb exposure.

Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field

International Nuclear Information System (INIS)

Tissue, D. T.; Lewis, J. D.; Wullschleger, S. D.; Amthro, J. S.; Griffin, K. L.; Anderson, O. R.

2002-01-01

The effects of elevated carbon dioxide and canopy position on leaf respiration in sweetgum trees in a closed canopy forest were measured in an effort to determine if, and why, enriched atmospheric carbon dioxide might affect leaf respiration in sweetgum. To account for the dark respiratory response to growth in elevated carbon dioxide, cell ultrastructure and cytochrome c oxidase activity in leaves were measured at different seasonal growth periods. Leaf respiration under light conditions was also estimated to determine whether elevated carbon dioxide affected daytime respiration. Results showed that long-term exposure to elevated carbon dioxide did not effect night-time or day- time respiration in trees grown in a plantation in the field. Canopy position affected night-time respiration partially, through the effects on leaf soluble sugar, starch, nitrogen and leaf mass per unit area. In carbon dioxide partial pressure the effects of canopy position were insignificant. It was concluded that elevated carbon dioxide does not directly impact leaf respiration in sweetgum and assuming no changes in leaf nitrogen or leaf chemical composition, the long-term effects on respiration in this species will be minimal. 50 refs., 4 tabs., 3 figs

Estimate of safe human exposure levels for lunar dust based on comparative benchmark dose modeling.

Science.gov (United States)

James, John T; Lam, Chiu-Wing; Santana, Patricia A; Scully, Robert R

2013-04-01

Brief exposures of Apollo astronauts to lunar dust occasionally elicited upper respiratory irritation; however, no limits were ever set for prolonged exposure to lunar dust. The United States and other space faring nations intend to return to the moon for extensive exploration within a few decades. In the meantime, habitats for that exploration, whether mobile or fixed, must be designed to limit human exposure to lunar dust to safe levels. Herein we estimate safe exposure limits for lunar dust collected during the Apollo 14 mission. We instilled three respirable-sized (∼2 μ mass median diameter) lunar dusts (two ground and one unground) and two standard dusts of widely different toxicities (quartz and TiO₂) into the respiratory system of rats. Rats in groups of six were given 0, 1, 2.5 or 7.5 mg of the test dust in a saline-Survanta® vehicle, and biochemical and cellular biomarkers of toxicity in lung lavage fluid were assayed 1 week and one month after instillation. By comparing the dose--response curves of sensitive biomarkers, we estimated safe exposure levels for astronauts and concluded that unground lunar dust and dust ground by two different methods were not toxicologically distinguishable. The safe exposure estimates were 1.3 ± 0.4 mg/m³ (jet-milled dust), 1.0 ± 0.5 mg/m³ (ball-milled dust) and 0.9 ± 0.3 mg/m³ (unground, natural dust). We estimate that 0.5-1 mg/m³ of lunar dust is safe for periodic human exposures during long stays in habitats on the lunar surface.

Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

Science.gov (United States)

Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

2013-08-01

Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

Saharan Dust Event Impacts on Cloud Formation and Radiation over Western Europe

Science.gov (United States)

Bangert, M.; Nenes, A.; Vogel, B.; Vogel, H.; Barahona, D.; Karydis, V. A.; Kumar, P.; Kottmeier, C.; Blahak, U.

2013-01-01

We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle-microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties. The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l-1 during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds. Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected). This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to -75Wm-2. Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80Wm-2, and the incoming long-wave radiation at the surface was increased significantly in the order of +10Wm-2. The strong radiative forcings associated with dust caused a reduction in surface temperature in the order of -0

Characterization of wood dust emission from hand-held woodworking machines.

Science.gov (United States)

Keller, F-X; Chata, F

2018-01-01

This article focuses on the prevention of exposure to wood dust when operating electrical hand-held sawing and sanding machines. A laboratory methodology was developed to measure the dust concentration around machines during operating processes. The main objective was to characterize circular saws and sanders, with the aim of classifying the different power tools tested in terms of dust emission (high dust emitter vs. low dust emitter). A test set-up was developed and is described and a measurement methodology was determined for each of the two operations studied. The robustness of the experimental results is discussed and shows good tendencies. The impact of air-flow extraction rate was assessed and the pressure loss of the system for each machine established. For the circular saws, three machines over the nine tested could be classified in the low dust emitter group. Their mean concentration values measured are between 0.64 and 0.98 mg/m 3 for the low dust emitter group and from 2.55 and 4.37 mg/m 3 for the high dust emitter group. From concentration measurements, a machine classification is possible-one for sanding machines and one for sawing machines-and a ratio from 1-7 is obtained when comparing the results. This classification will be helpful when a choice of high performance power tools, in terms of dust emission, must be made by professionals.

Changes in mitochondrial respiration in the human placenta over gestation.

Science.gov (United States)

Holland, Olivia J; Hickey, Anthony J R; Alvsaker, Anna; Moran, Stephanie; Hedges, Christopher; Chamley, Lawrence W; Perkins, Anthony V

2017-09-01

Placental mitochondria are subjected to micro-environmental changes throughout gestation, in particular large variations in oxygen. How placental mitochondrial respiration adapts to changing oxygen concentrations remains unexplored. Additionally, placental tissue is often studied in culture; however, the effect of culture on placental mitochondria is unclear. Placental tissue was obtained from first trimester and term (laboured and non-laboured) pregnancies, and selectively permeabilized to access mitochondria. Respirometry was used to compare respiration states and substrate use in mitochondria. Additionally, explants of placental tissue were cultured for four, 12, 24, 48, or 96 h and respiration measured. Mitochondrial respiration decreased at 11 weeks compared to earlier gestations (p = 0.05-0.001), and mitochondrial content increased at 12-13 weeks compared to 7-10 weeks (p = 0.042). In term placentae, oxidative phosphorylation (OXPHOS) through mitochondrial complex IV (p Respiration was increased (p ≤ 0.006-0.001) in laboured compared to non-laboured placenta. After four hours of culture, respiration was depressed compared to fresh tissue from the same placenta and continued to decline with time in culture. Markers of apoptosis were increased, while markers of autophagy, mitochondrial biogenesis, and mitochondrial membrane potential were decreased after four hours of culture. Respiration and mitochondrial content alter over gestation/with labour. Decreased respiration at 11 weeks and increased mitochondrial content at 12-13 weeks may relate to onset of maternal blood flow, and increased respiration as a result of labour may be an adaptation to ischaemia-reperfusion. At term, mitochondria were more susceptible to changes in respiratory function relative to first trimester when cultured in vitro, perhaps reflecting changes in metabolic demands as gestation progresses. Metabolic plasticity of placental mitochondria has relevance to placenta

Introduction to project DUNE, a DUst experiment in a low Nutrient, low chlorophyll Ecosystem

Science.gov (United States)

Guieu, C.; Dulac, F.; Ridame, C.; Pondaven, P.

2014-01-01

The main goal of project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of eolian mineral dust. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension after atmospheric deposition at the sea surface. This introductory paper describes the objectives of DUNE and the implementation plan of a series of mesocosm experiments conducted in the Mediterranean Sea in 2008 and 2010 during which either wet or dry and a succession of two wet deposition fluxes of 10 g m-2 of Saharan dust have been simulated based on the production of dust analogs from erodible soils of a source region. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented. From laboratory results on the solubility of trace elements in dust to biogeochemical results from the mesocosm experiments and associated modeling, these papers describe how the strong simulated dust deposition events impacted the marine biogeochemistry. Those multidisciplinary results are bringing new insights into the role of atmospheric deposition on oligotrophic ecosystems and its impact on the carbon budget. The dissolved trace metals with crustal origin - Mn, Al and Fe - showed different behaviors as a function of time after the seeding. The increase in dissolved Mn and Al concentrations was attributed to dissolution processes. The observed decrease in dissolved Fe was due to scavenging on sinking dust particles and aggregates. When a second dust seeding followed, a dissolution of Fe from the dust particles was then observed due to the excess Fe binding ligand concentrations present at that time. Calcium nitrate and sulfate were formed in the dust

Investigating a novel flame retardant known as V6: measurements in baby products, house dust, and car dust.

Science.gov (United States)

Fang, Mingliang; Webster, Thomas F; Gooden, David; Cooper, Ellen M; McClean, Michael D; Carignan, Courtney; Makey, Colleen; Stapleton, Heather M

2013-05-07

With the phase-out of polybrominated diphenyl ether (PBDE) flame retardants, the use of new and alternate flame retardants has been increasing. 2,2-bis(chloromethyl)propane-1,3-diyltetrakis(2-chloroethyl) bisphosphate, known as V6, is a flame retardant applied to polyurethane foam commonly found in furniture and automobile foam. However, to the authors' knowledge, no research has been conducted on V6 levels in the environment. The intention of this study was to measure the concentration of V6 in foam collected from baby products where it was recently detected and measure levels in dust samples collected from homes and automobiles in the Boston, MA area. To accomplish this, a pure V6 commercial standard was purchased from a Chinese manufacturer and purified (>98%). An analytical method to measure V6 in dust samples using liquid chromatography tandem mass spectrometry (LC/MS-MS) was developed. Extraction was conducted using accelerated solvent extraction (ASE) and extracts were purified using an ENVI-Florisil SPE column (500 mg, 3 mL). V6 was measured in foam samples collected from baby products with a concentration ranging from 24,500,000 to 59,500,000 ng/g of foam (n = 12, average ± sd: 46,500,000 ± 12,000,000 ng/g; i.e., on average, 4.6% of the foam mass was V6). V6 was also detected in 19 of 20 car dust samples and 14 of 20 house dust samples analyzed. The concentration of V6 in the house dust ranged from <5 ng/g to 1110 ng/g with a median of 12.5 ng/g, and <5 ng/g to 6160 ng/g in the car dust with a median of 103.0 ng/g. Concentrations in car dust were significantly higher than in the house dust potentially indicating higher use of V6 in automobiles compared to products found in the home. Furthermore, tris (2-chloroethyl) phosphate (TCEP), a known carcinogen, was found in the V6 commercial mixture (14% by weight) as an impurity and was consistently detected with V6 in the foam samples analyzed. A significant correlation was also observed between V6 and TCEP in

Sustained stimulation of soil respiration after 10 years of experimental warming

International Nuclear Information System (INIS)

Reth, S; Graf, W; Reichstein, M; Munch, J C

2009-01-01

A number of forest and grassland studies indicated that stimulation of the soil respiration by soil warming ceases after a couple of years (Luo et al 2001 Nature 413 622-5). Here we present results from a long-term soil warming lysimeter experiment in southern Germany showing sustained stimulation of soil respiration after 10 years. Moreover, both warmed and control treatments exhibited a similar temperature response of soil respiration, indicating that adaptation in terms of temperature sensitivity was absent. Carbon dioxide concentration measurements within the profiles are supporting these findings. The increased soil respiration occurred although vegetation productivity in the warmed treatment was not higher than in the control plots. These findings strongly contrast with current soil carbon modeling concepts, where carbon pools decay according to first-order kinetics, and thus a depletion of labile soil carbon pools leads to an apparent down-regulation of microbial respiration (Knorr et al 2005 Nature 433 298-301). Consequently, the potential for positive climate carbon cycle feedback may be larger than represented in current models of soil carbon turnover.

Pantoea agglomerans: a mysterious bacterium of evil and good. Part II--Deleterious effects: Dust-borne endotoxins and allergens--focus on grain dust, other agricultural dusts and wood dust.

Science.gov (United States)

Dutkiewicz, Jacek; Mackiewicz, Barbara; Lemieszek, Marta Kinga; Golec, Marcin; Skórska, Czesława; Góra-Florek, Anna; Milanowski, Janusz

2016-01-01

Pantoea agglomerans, a Gram-negative bacterium developing in a variety of plants as epiphyte or endophyte is particularly common in grain and grain dust, and has been identified by an interdisciplinary group from Lublin, eastern Poland, as a causative agent of work-related diseases associated with exposure to grain dust and other agricultural dusts. The concentration of P. agglomerans in grain as well as in the settled grain and flour dust was found to be high, ranging from 10(4)-10(8) CFU/g, while in the air polluted with grain or flour dust it ranged from 10(3)-10(5) CFU/m(3) and formed 73.2-96% of the total airborne Gram-negative bacteria. The concentration of P. agglomerans was also relatively high in the air of the facilities processing herbs and other plant materials, while it was lower in animal farms and in wood processing facilities. Pantoea agglomerans produces a biologically-potent endotoxin (cell wall lipopolysaccharide, LPS). The significant part of this endotoxin occurs in dusts in the form of virus-sized globular nanoparticles measuring 10-50 nm that could be described as the 'endotoxin super-macromolecules'. A highly significant relationship was found (R=0.804, P=0.000927) between the concentration of the viable P. agglomerans in the air of various agricultural and wood industry settings and the concentration of bacterial endotoxin in the air, as assessed by the Limulus test. Although this result may be interfered by the presence of endotoxin produced by other Gram-negative species, it unequivocally suggests the primary role of the P. agglomerans endotoxin as an adverse agent in the agricultural working environment, causing toxic pneumonitis (ODTS). Numerous experiments by the inhalation exposure of animals to various extracts of P. agglomerans strains isolated from grain dust, including endotoxin isolated with trichloroacetic acid (LPS-TCA), endotoxin nanoparticles isolated in sucrose gradient (VECN), and mixture of proteins and endotoxin obtained

Effect of gas and dust emissions on respiration and chemical constituents of Parmelia physodes

Energy Technology Data Exchange (ETDEWEB)

Klee, R

1970-01-01

Pieces of bark covered with Parmelia physodes were punched out and placed into plastic plates. These explants were tested as bioindicators for air pollution in outdoor exposure and under controlled laboratory conditions. The outdoor experiments were carried out at Frankfurt M. For the laboratory experiments, SO/sub 2/ and coke ash (often found as components of air pollution) were chosen. The criteria used to evaluate the effects of emissions were mortality rate, the intensity of respiration, the destruction of chloroplast and an increase in organic and inorganic sulfur.

Foam property tests to evaluate the potential for longwall shield dust control.

Science.gov (United States)

Reed, W R; Beck, T W; Zheng, Y; Klima, S; Driscoll, J

2018-01-01

Tests were conducted to determine properties of four foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with the Mine Safety and Health Administration's lower coal mine respirable dust standard of 1.5 mg/m 3 . Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used low-pressure air generated by a blower and water pressure using a foam generator developed by the U.S. National Institute for Occupational Safety and Health. Foam property tests, consisting of a foam expansion ratio test and a water drainage test, were conducted to classify foams. Compressed-air-generated foams tended to have low expansion ratios, from 10 to 19, with high water drainage. Blower-air-generated foams had higher foam expansion ratios, from 30 to 60, with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The test results eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control.

Quantitative determination of alpha-quartz in airborne dust samples by x-ray diffraction

International Nuclear Information System (INIS)

Bayon, A.; Roca, M.

1982-01-01

The quantitative determination by X-ray diffractometry of alpha-quartz In airborne respirable dust samples on silver membrane filters is considered. A cobalt anode X-ray tube Is employed. NiO is used as Internal standard In order to compensate for both the variations of specimen absorption and the effect due to the nonuniformity of the incident X-ray beam and to the incomplete homogeneity on the filters of samples and standards. (Author) 17 refs

Quantitative determination of alpha-quartz in airbone dust samples by X-ray diffraction

International Nuclear Information System (INIS)

Bayon, A.; Roca, M.

1982-01-01

The quantitative determination by X-ray diffractometry of alpha-quartz in airbone respirable dust samples on silver membrane filters is considered. A cobalt anode X-ray tube is employec. NiO is used as internal standard in order to compensate for both the variations of specimen absorption and the effect due to the nonuniformity of the incident X-ray beam and to the incomplete homogeneity on the filters of samples and standards. (auth.) [es

High temperature and dust load in mines

Energy Technology Data Exchange (ETDEWEB)

Sukhanov, V V; Bolonova, L N; Donets, I K; Mukhina, K Sh

1989-02-01

Presents results of study of combined load on the human system of heat and dust as encountered in deep coal mines in the Donbass. Groups of coal miners were studied to ascertain the state of their lungs, particularly the presence of free silica, dust, collagen, etc. The sickness records for a number of Donbass mining associations for the past 25 years were analyzed. Multiple regression analysis of the data obtained led to curves relating the number of shifts worked to dust levels, pulmonary ventilation (0.01 and 0.04 m/sup 3//min) and maximum admissible dust concentrations (2, 4, 6 and 10 mg/m/sup 3/). In the 25-35 C temperature range a rise of 1 C is accompanied by increases of 9.9% in dust mass, 15.4% in silica content, 10.7% in mineral impurities and 2.3% in pathomorphological changes in the lungs. An adjustment to the maximum admissible concentration correction coefficient of 10% for every 1 C over 26 C is recommended. 1 ref.

Respirators. Does your face fit

Energy Technology Data Exchange (ETDEWEB)

Caro, N M; Else, D

1981-04-01

The authors carried out a survey of face sizes of men and women of four different ethnic origins and carried out face-seal leakage trials on four corresponding test panels. No single respirator design is likely to fit all members of the workforce, and it may be necessary to stock respirators from more than one manufacturers.Three or four different respirators or size of respirator may be needed. However, the use of lossely-fitting respirators such as Airsteam helmets could remove the necessity for exhaustive fitting procedures.

Boreal and temperate trees show strong acclimation of respiration to warming.

Science.gov (United States)

Reich, Peter B; Sendall, Kerrie M; Stefanski, Artur; Wei, Xiaorong; Rich, Roy L; Montgomery, Rebecca A

2016-03-31

Plant respiration results in an annual flux of carbon dioxide (CO2) to the atmosphere that is six times as large as that due to the emissions from fossil fuel burning, so changes in either will impact future climate. As plant respiration responds positively to temperature, a warming world may result in additional respiratory CO2 release, and hence further atmospheric warming. Plant respiration can acclimate to altered temperatures, however, weakening the positive feedback of plant respiration to rising global air temperature, but a lack of evidence on long-term (weeks to years) acclimation to climate warming in field settings currently hinders realistic predictions of respiratory release of CO2 under future climatic conditions. Here we demonstrate strong acclimation of leaf respiration to both experimental warming and seasonal temperature variation for juveniles of ten North American tree species growing for several years in forest conditions. Plants grown and measured at 3.4 °C above ambient temperature increased leaf respiration by an average of 5% compared to plants grown and measured at ambient temperature; without acclimation, these increases would have been 23%. Thus, acclimation eliminated 80% of the expected increase in leaf respiration of non-acclimated plants. Acclimation of leaf respiration per degree temperature change was similar for experimental warming and seasonal temperature variation. Moreover, the observed increase in leaf respiration per degree increase in temperature was less than half as large as the average reported for previous studies, which were conducted largely over shorter time scales in laboratory settings. If such dampening effects of leaf thermal acclimation occur generally, the increase in respiration rates of terrestrial plants in response to climate warming may be less than predicted, and thus may not raise atmospheric CO2 concentrations as much as anticipated.

New method of measuring lichen respiration: response of selected species to temperature, pH and sulphur dioxide

Energy Technology Data Exchange (ETDEWEB)

Baddeley, M S; Ferry, B W; Finegan, E J

1971-01-01

The respiration of selected lichens and their response to temperature, pH and sulphur dioxide concentration were investigated in aqueous solution using an oxygen electrode. Respiration rates increased to a maximum at 40/sup 0/ C although some individual species showed variations from this general pattern. The optimal pH for respiration was found to be 4.2 except in Hypogymnia physodes (3.2) and Ramalina fastigiata (5.2). Sulfur dioxide at concentrations similar to those likely to be encountered in heavily polluted areas in nature had marked inhibitory effects of the respiration rate of all species investigated but as these variations did not entirely correspond to the tolerances of the species in the field some other factors must also be involved in the sensitivity of lichens to sulphur dioxide pollution. The advantages of using an oxygen electrode rather than manometric or other techniques in studies on the respiration rate of lichens are discussed. 29 references, 3 figures, 2 tables.

Evaluation of a Shaker Dust Collector for Use in a Recirculating Ventilation System.

Science.gov (United States)

Peters, Thomas M; Sawvel, Russell A; Park, Jae Hong; Anthony, T Renée

2015-01-01

General ventilation with recirculated air may be cost-effective to control the concentration of low-toxicity, contaminants in workplaces with diffuse, dusty operations, such as in agriculture. Such systems are, however, rarely adopted with little evidence showing improved air quality and ability to operate under harsh conditions. The goal of this work was to examine the initial and long-term performance of a fabric-filter shaker dust collector (SDC) in laboratory tests and as deployed within a recirculating ventilation system in an agricultural building. In laboratory tests, collection efficiency and pressure drop were tracked over several filter loading cycles, and the recovery of filter capacity (pressure drop) from filter shaking was examined. Collection efficiencies of particles larger than 5 μm was high (>95%) even when the filter was pristine, showing effective collection of large particles that dominate inhalable concentrations typical of agricultural dusts. For respirable-sized particles, collection efficiencies were low when the filter was pristine (e.g., 27% for 1 μm) but much higher when a dust cake developed on the filter (>99% for all size particles), even after shaking (e.g., 90% for 1 μm). The first shake of a filter was observed to recovery a substantial fraction of filter capacity, with subsequent shakes providing little benefit. In field tests, the SDC performed effectively over a period of three months in winter when incorporated in a recirculating ventilation system of a swine farrowing room. Trends in collection efficiency and pressure drop with loading were similar to those observed in the laboratory with overall collection efficiencies high (>80%) when pressure drop exceeded 230 Pa, or 23% of the maximum loading recommended by the manufacturer. This work shows that the SDC can function effectively over the harsh winter in swine rearing operations. Together with findings of improved air quality in the farrowing room reported in a

Computational algorithm for molybdenite concentrate annealing

International Nuclear Information System (INIS)

Alkatseva, V.M.

1995-01-01

Computational algorithm is presented for annealing of molybdenite concentrate with granulated return dust and that of granulated molybdenite concentrate. The algorithm differs from the known analogies for sulphide raw material annealing by including the calculation of return dust mass in stationary annealing; the latter quantity varies form the return dust mass value obtained in the first iteration step. Masses of solid products are determined by distribution of concentrate annealing products, including return dust and benthonite. The algorithm is applied to computations for annealing of other sulphide materials. 3 refs

Effects of uniformities of deposition of respirable particles on filters on determining their quartz contents by using the direct on-filter X-ray diffraction (DOF XRD) method.

Science.gov (United States)

Chen, Ching-Hwa; Tsaia, Perng-Jy; Lai, Chane-Yu; Peng, Ya-Lian; Soo, Jhy-Charm; Chen, Cheng-Yao; Shih, Tung-Sheng

2010-04-15

In this study, field samplings were conducted in three workplaces of a foundry plant, including the molding, demolding, and bead blasting, respectively. Three respirable aerosol samplers (including a 25-mm aluminum cyclone, nylon cyclone, and IOSH cyclone) were used side-by-side to collect samples from each selected workplace. For each collected sample, the uniformity of the deposition of respirable dusts on the filter was measured and its free silica content was determined by both the DOF XRD method and NIOSH 7500 XRD method (i.e., the reference method). A same trend in measured uniformities can be found in all selected workplaces: 25-mm aluminum cyclone>nylon cyclone>IOSH cyclone. Even for samples collected by the sampler with the highest uniformity (i.e., 25-mm aluminum cyclone), the use of the DOF XRD method would lead to the measured free silica concentrations 1.15-2.89 times in magnitude higher than that of the reference method. A new filter holder should be developed with the minimum uniformity comparable to that of NIOSH 7500 XRD method (=0.78) in the future. The use of conversion factors for correcting quartz concentrations obtained from the DOF XRD method based on the measured uniformities could be suitable for the foundry industry at this stage. 2009 Elsevier B.V. All rights reserved.

Separating rhizosphere respiration from total soil respiration in two larch plantations in northeastern China.

Science.gov (United States)

Jiang, Lifen; Shi, Fuchen; Li, Bo; Luo, Yiqi; Chen, Jiquan; Chen, Jiakuan

2005-09-01

The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 micromol m(-2) s(-1) in winter to 6.0 micromol m(-2) s(-1) in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 micromol m(-2) s(-1) in the old forest and from 0.3 to 4.0 micromol m(-2) s(-1) in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.

Respirator use and its impact on particulate matter exposure in aluminum manufacturing facilities.

Science.gov (United States)

Liu, Sa; Noth, Elizabeth; Eisen, Ellen; Cullen, Mark R; Hammond, Katharine

2018-05-31

Objectives As part of a large epidemiologic study of particulate health effect, this study aimed to report respirator use among total particulate matter (TPM) samples collected in a major aluminum manufacturing company from 1966‒2013 and evaluate the impact of respirator-use adjustment on exposure estimation. Methods Descriptive analyses were performed to evaluate respirator use across facilities and by facility type and job. Protection factors were applied to TPM measurements for recorded respirator use. Estimated TPM exposure for each job ‒ before and after respirator-use adjustment ‒ were compared to assess the impact of adjustment on exposure estimation. Results Respirator use was noted for 37% of 12 402 full-shift personal TPM samples. Measured TPM concentration ranged from less than detectable to 8220 mg/m3, with arithmetic mean, median and standard deviation being 10.6, 0.87 and 130 mg/m 3 , respectively. Respirators were used more often in smelting facilities (52% of TPM measurements) than in fabricating (17%) or refinery facilities (28%) (Pfacilities were subject to respirator-use adjustment, whereas it was 20% and 70% in fabricating and refinery facilities, respectively. Applying protection factors to TPM measurements significantly reduced estimated job mean TPM exposures and changed exposure categories in these facilities, with larger impact in smelting than fabricating facilities. Conclusions Respirator use varied by time, facility and job. Adjusting respirator use resulted in differential impact in smelting and fabricating facilities, which will need to be incorporated into ongoing epidemiologic studies accordingly.

Respirator field performance factors

International Nuclear Information System (INIS)

Skaggs, B.J.; DeField, J.D.; Strandberg, S.W.; Sutcliffe, C.R.

1985-01-01

The Industrial Hygiene Group assisted OSHA and the NRC in measurements of respirator performance under field conditions. They reviewed problems associated with sampling aerosols within the respirator in order to determine fit factors (FFs) or field performance factor (FPF). In addition, they designed an environmental chamber study to determine the effects of temperature and humidity on a respirator wearer

Pantoea agglomerans : a mysterious bacterium of evil and good. Part II. Deleterious effects: Dust-borne endotoxins and allergens – focus on grain dust, other agricultural dusts and wood dust

Directory of Open Access Journals (Sweden)

Jacek Dutkiewicz

2015-12-01

Full Text Available Pantoea agglomerans , a Gram-negative bacterium developing in a variety of plants as epiphyte or endophyte is particularly common in grain and grain dust, and has been identified by an interdisciplinary group from Lublin, eastern Poland, as a causative agent of work-related diseases associated with exposure to grain dust and other agricultural dusts. The concentration of [i]P. agglomerans[/i] in grain as well as in the settled grain and flour dust was found to be high, ranging from 10 4 –10 8 CFU/g, while in the air polluted with grain or flour dust it ranged from 10 3 –10 5 CFU/m 3 and formed 73.2–96% of the total airborne Gram-negative bacteria. The concentration of P. agglomerans was also relatively high in the air of the facilities processing herbs and other plant materials, while it was lower in animal farms and in wood processing facilities. Pantoea agglomerans produces a biologically-potent endotoxin (cell wall lipopolysaccharide, LPS. The significant part of this endotoxin occurs in dusts in the form of virus-sized globular nanoparticles measuring 10–50 nm that could be described as the ‘endotoxin super-macromolecules’. A highly significant relationship was found (R=0.804, P=0.000927 between the concentration of the viable P. agglomerans in the air of various agricultural and wood industry settings and the concentration of bacterial endotoxin in the air, as assessed by the Limulus test. Although this result may be interfered by the presence of endotoxin produced by other Gram-negative species, it unequivocally suggests the primary role of the P. agglomerans endotoxin as an adverse agent in the agricultural working environment, causing toxic pneumonitis (ODTS. Numerous experiments by the inhalation exposure of animals to various extracts of P. agglomerans strains isolated from grain dust, including endotoxin isolated with trichloroacetic acid (LPS-TCA, endotoxin nanoparticles isolated in sucrose gradient (VECN, and mixture of

Saharan dust event impacts on cloud formation and radiation over Western Europe

Directory of Open Access Journals (Sweden)

M. Bangert

2012-05-01

Full Text Available We investigated the impact of mineral dust particles on clouds, radiation and atmospheric state during a strong Saharan dust event over Europe in May 2008, applying a comprehensive online-coupled regional model framework that explicitly treats particle microphysics and chemical composition. Sophisticated parameterizations for aerosol activation and ice nucleation, together with two-moment cloud microphysics are used to calculate the interaction of the different particles with clouds depending on their physical and chemical properties.

The impact of dust on cloud droplet number concentration was found to be low, with just a slight increase in cloud droplet number concentration for both uncoated and coated dust. For temperatures lower than the level of homogeneous freezing, no significant impact of dust on the number and mass concentration of ice crystals was found, though the concentration of frozen dust particles reached up to 100 l⁻¹ during the ice nucleation events. Mineral dust particles were found to have the largest impact on clouds in a temperature range between freezing level and the level of homogeneous freezing, where they determined the number concentration of ice crystals due to efficient heterogeneous freezing of the dust particles and modified the glaciation of mixed phase clouds.

Our simulations show that during the dust events, ice crystals concentrations were increased twofold in this temperature range (compared to if dust interactions are neglected. This had a significant impact on the cloud optical properties, causing a reduction in the incoming short-wave radiation at the surface up to −75 W m⁻². Including the direct interaction of dust with radiation caused an additional reduction in the incoming short-wave radiation by 40 to 80 W m⁻², and the incoming long-wave radiation at the surface was increased significantly in the order of +10 W m⁻².

The

Creation of Wood Dust during Wood Processing: Size Analysis, Dust Separation, and Occupational Health

Directory of Open Access Journals (Sweden)

Eva Mračková

2015-11-01

Full Text Available Mechanical separators and fabric filters are being used to remove airborne fine particles generated during the processing and handling of wood. Such particles might have a harmful effect on employee health, not only in small- but also in large-scale wood processing facilities. The amount of wood dust and its dispersion conditions vary according to geometric boundary conditions. Thus, the dispersion conditions could be changed by changing the linear size of the particles. Moreover, the smaller the particles are, the more harmful they can be. It is necessary to become familiar with properties, from a health point of view, of wood dust generated from processing. Wood dust has to be sucked away from the processing area. The fractional separation efficiency of wood dust can be improved using exhaust and filtering devices. Filtration efficiency depends on moisture content, particle size, and device performance. Because of the carcinogenicity of wood dust, the concentration of wood dust in air has to be monitored regularly. Based on the results hereof, a conclusion can be made that both mechanical separators of types SEA and SEB as well as the fabric filters with FINET PES 1 textile are suitable for the separation of wet saw dust from all types of wooden waste produced within the process.

Soil Respiration And Respiration Partitioning In An Oak-Savannah With A History Of Fertilization

Science.gov (United States)

Morris, K. A.; Nair, R.; Schrumpf, M.; Migliavacca, M.

2017-12-01

Soil respiration is a combination of autotrophic and heterotrophic components. These components have different controls and structurally complex ecosystems such as oak-savannahs offer an opportunity to study strongly contrasting conditions (ie., soil from under trees versus open areas) in an environment with similar soil mineralogy and climatic patterns. To measure respiration coming from plant roots, fungal hyphae, and free-living microbes we established stations of soil cores comprised of three selectively permeable meshes under tree canopies and in open grassy areas of a Holm Oak (Quercus ilex) savannah in Extremadura, Spain. Large plots of this ecosystem had previously been fertilized as part of a stoichiometeric imbalance study (in 2015). Stations were installed in Dec. 2016 within four plots; control, N added, P added, and N+P added. Respiration from cores was measured in campaigns at key phenological stages with a portable Li-Cor 8100A unit. Six months after installation > 50% of soil respiration was attributable to free-living microbes. There is a persistent effect of the prior fertilization, resulting in increased soil respiration in open areas regardless of fertilizer type, while respiration from under tree canopies had a varied response. Soil under tree canopies showed distinct sensitivity to stoichiometric imbalance, meaning that addition of N or P alone either did not change respiration or decreased it slightly, while N+P stimulated respiration. We determined that respiration from free-living microbes is a major component of soil respiration even in the most active plant growing season. However, because of the lag between the time of fertilization and the time of measurement, it not possible to say whether treatment responses are due solely to nutrient status of the soil or whether changes in plant biomass and species composition also play a role. Additional work planned at the site will shed light on this uncertainty as well as the contribution of

Phthalate and PAH concentrations in dust collected from Danish homes and daycare centers

DEFF Research Database (Denmark)

Langer, Sarka; Weschler, Charles J.; Fischer, Andreas

2010-01-01

(diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), di(isobutyl) phthalate (DiBP), butyl benzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP)) and three PAHs (pyrene, benz[a]anthracene (B[a]A) and benzo[a]pyrene (B[a]P)). The three PAHs and DEHP were detected in dust samples from all sites, while...... DEP. DnBP, DiBP and BBzP were detected in more than 75% of the bedrooms and more than 90% of the daycare centers. The dust mass-fractions of both phthalates and PAHs were log-normally distributed. With the exception of DEP, the mass-fractions of phthalates in dust were higher in daycare centers than...... homes: PAH mass-fractions in dust were similar in the two locations. There was no correlation among the different phthalates in either homes or daycare centers. In contrast, the PAH were correlated with one another more strongly so in homes (R-2 = 0.80-0.90) than in daycare centers (R-2 = 0...

Desert Dust Outbreaks in Southern Europe: Contribution to Daily PM10 Concentrations and Short-Term Associations with Mortality and Hospital Admissions

Science.gov (United States)

Stafoggia, Massimo; Zauli-Sajani, Stefano; Pey, Jorge; Samoli, Evangelia; Alessandrini, Ester; Basagaña, Xavier; Cernigliaro, Achille; Chiusolo, Monica; Demaria, Moreno; Díaz, Julio; Faustini, Annunziata; Katsouyanni, Klea; Kelessis, Apostolos G.; Linares, Cristina; Marchesi, Stefano; Medina, Sylvia; Pandolfi, Paolo; Pérez, Noemí; Querol, Xavier; Randi, Giorgia; Ranzi, Andrea; Tobias, Aurelio; Forastiere, Francesco

2015-01-01

Background: Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. Objectives: We aimed to estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 Southern European cities, distinguishing between PM10 originating from the desert and from other sources. Methods: We identified desert dust advection days in multiple Mediterranean areas for 2001–2010 by combining modeling tools, back-trajectories, and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. Results: On average, 15% of days were affected by desert dust at ground level (desert PM10 > 0 μg/m3). Most episodes occurred in spring–summer, with increasing gradient of both frequency and intensity north–south and west–east of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10 μg/m3 in non-desert and desert PM10 (lag 0–1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. Conclusions: PM10 originating from the desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections. Citation: Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, Cernigliaro A, Chiusolo M, Demaria M, Díaz J, Faustini A

Desert Dust Outbreaks in Southern Europe: Contribution to Daily PM₁₀ Concentrations and Short-Term Associations with Mortality and Hospital Admissions.

Science.gov (United States)

Stafoggia, Massimo; Zauli-Sajani, Stefano; Pey, Jorge; Samoli, Evangelia; Alessandrini, Ester; Basagaña, Xavier; Cernigliaro, Achille; Chiusolo, Monica; Demaria, Moreno; Díaz, Julio; Faustini, Annunziata; Katsouyanni, Klea; Kelessis, Apostolos G; Linares, Cristina; Marchesi, Stefano; Medina, Sylvia; Pandolfi, Paolo; Pérez, Noemí; Querol, Xavier; Randi, Giorgia; Ranzi, Andrea; Tobias, Aurelio; Forastiere, Francesco

2016-04-01

Evidence on the association between short-term exposure to desert dust and health outcomes is controversial. We aimed to estimate the short-term effects of particulate matter ≤ 10 μm (PM10) on mortality and hospital admissions in 13 Southern European cities, distinguishing between PM10 originating from the desert and from other sources. We identified desert dust advection days in multiple Mediterranean areas for 2001-2010 by combining modeling tools, back-trajectories, and satellite data. For each advection day, we estimated PM10 concentrations originating from desert, and computed PM10 from other sources by difference. We fitted city-specific Poisson regression models to estimate the association between PM from different sources (desert and non-desert) and daily mortality and emergency hospitalizations. Finally, we pooled city-specific results in a random-effects meta-analysis. On average, 15% of days were affected by desert dust at ground level (desert PM10 > 0 μg/m3). Most episodes occurred in spring-summer, with increasing gradient of both frequency and intensity north-south and west-east of the Mediterranean basin. We found significant associations of both PM10 concentrations with mortality. Increases of 10 μg/m3 in non-desert and desert PM10 (lag 0-1 days) were associated with increases in natural mortality of 0.55% (95% CI: 0.24, 0.87%) and 0.65% (95% CI: 0.24, 1.06%), respectively. Similar associations were estimated for cardio-respiratory mortality and hospital admissions. PM10 originating from the desert was positively associated with mortality and hospitalizations in Southern Europe. Policy measures should aim at reducing population exposure to anthropogenic airborne particles even in areas with large contribution from desert dust advections. Stafoggia M, Zauli-Sajani S, Pey J, Samoli E, Alessandrini E, Basagaña X, Cernigliaro A, Chiusolo M, Demaria M, Díaz J, Faustini A, Katsouyanni K, Kelessis AG, Linares C, Marchesi S, Medina S, Pandolfi P, P�

Effects of thyroid state on respiration of perfused rat and guinea pig hearts

International Nuclear Information System (INIS)

Read, L.C.; Wallace, P.G.; Berry, M.N.

1987-01-01

The effects of thyroid state on the respiration of the isolated heart were investigated using retrograde perfused rat and guinea pig hearts. In both species, hypothyroidism caused a marked depression in circulating thyroid hormone concentrations and in the respiration of the isolated, retrograde perfused heart. Hypothyroidism was caused by injecting animals with Na 131 I. The effects on myocardial respiration could be attributed to changes in the contraction frequency and in the oxygen consumption per beat, with little contribution from basal respiration. Treatment of animals with thyroxine elevated plasma thyroid hormones to a similar extent in rats and guinea pigs. In the latter, thyroxine treatment was associated with substantial increases in the contraction frequency and the oxygen consumption per beat of the isolated heart. In contrast, only small changes were apparent in the retrograde perfused rat heart, observations that were confirmed in rat hearts perfused at near physiological work loads. It was concluded that rat hearts isolated from normal animals function at near maximal thyroid state, in contrast to the guinea pig heart, which requires higher circulating concentrations of thyroid hormones to attain maximal responses

Ventilation in homes infested by house-dust mites.

Science.gov (United States)

Sundell, J; Wickman, M; Pershagen, G; Nordvall, S L

1995-02-01

Thirty single-family homes with either high (> or = 2000 ng/g) or low (< or = 1000 ng/g) house-dust mite (HDM) allergen levels in mattress dust were examined for ventilation, thermal climate, and air quality (formaldehyde and total volatile organic compounds (TVOC). Elevated concentrations of HDM allergen in mattress and floor dust were associated with the difference in absolute humidity between indoor and outdoor air, as well as with low air-change rates of the home, particularly the bedroom. No correlation was found between concentration of TVOC or formaldehyde in bedroom air and HDM allergen concentration. In regions with a cold winter climate, the air-change rate of the home and the infiltration of outdoor air into the bedroom appear to be important for the infestation of HDM.

Classification of Dust Days by Satellite Remotely Sensed Aerosol Products

Science.gov (United States)

Sorek-Hammer, M.; Cohen, A.; Levy, Robert C.; Ziv, B.; Broday, D. M.

2013-01-01

Considerable progress in satellite remote sensing (SRS) of dust particles has been seen in the last decade. From an environmental health perspective, such an event detection, after linking it to ground particulate matter (PM) concentrations, can proxy acute exposure to respirable particles of certain properties (i.e. size, composition, and toxicity). Being affected considerably by atmospheric dust, previous studies in the Eastern Mediterranean, and in Israel in particular, have focused on mechanistic and synoptic prediction, classification, and characterization of dust events. In particular, a scheme for identifying dust days (DD) in Israel based on ground PM10 (particulate matter of size smaller than 10 nm) measurements has been suggested, which has been validated by compositional analysis. This scheme requires information regarding ground PM10 levels, which is naturally limited in places with sparse ground-monitoring coverage. In such cases, SRS may be an efficient and cost-effective alternative to ground measurements. This work demonstrates a new model for identifying DD and non-DD (NDD) over Israel based on an integration of aerosol products from different satellite platforms (Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI)). Analysis of ground-monitoring data from 2007 to 2008 in southern Israel revealed 67 DD, with more than 88 percent occurring during winter and spring. A Classification and Regression Tree (CART) model that was applied to a database containing ground monitoring (the dependent variable) and SRS aerosol product (the independent variables) records revealed an optimal set of binary variables for the identification of DD. These variables are combinations of the following primary variables: the calendar month, ground-level relative humidity (RH), the aerosol optical depth (AOD) from MODIS, and the aerosol absorbing index (AAI) from OMI. A logistic regression that uses these variables, coded as binary

The management of house dust mite allergies

NARCIS (Netherlands)

Bronswijk, van J.E.M.H.; Schober, G.; Kniest, F.M.

1990-01-01

A safe and practical home sanitation procedure for the removal of house dust mites (Dermatophagoides pteronyssinus) and their allergens is described. The severity of mite infestation was assessed with the use of the Acarex test, which measures the concentration of guanine in house dust, and all

Magnetic studies of dusts in the urban environment

International Nuclear Information System (INIS)

Xie, S.

2000-12-01

Dusts are one of the major public health concerns in the urban environment. This study investigates the application of magnetic techniques in the studies of urban dust pollution. Measurements of magnetic properties, element concentrations, and the organic matter content were carried out on Liverpool (UK) street dust and/or Bootle (UK) deposited dust. Mixed dominant ferrimagnetic phases are found in Liverpool street dust although magnetite is probably a major one. The partial susceptibility technique is able to model the contributions of main magnetic components satisfactorily in Liverpool street dust. There are similar spatial distributions for some measurements, such as χLF and Pb, whilst there are different patterns for some measurements, such as χLF and the organic matter content. There are good linear correlations between the organic matter content and some magnetic mineral concentration-related parameters for < 1mm (bulk) samples. Among them, frequency dependent susceptibility (χFD) shows the highest correlation coefficient value. χFD percentage demonstrates a significant correlation with the organic matter content for size fraction and bulk samples. This suggests that re-entrainment of soil is probably a major source of the organic material present in street dust. The ratio χARM /SIRM shows a highly significant correlation with the organic matter content for <150μm fraction samples. The study demonstrates that the simple, rapid, and non-destructive magnetic measurements may be used as proxies for the organic matter content in street dust. Associations between magnetic properties and element concentrations are investigated by using correlation analysis and factor analysis, which may be a potential approach for source identification of magnetic material in the environment. The study suggests that ferrimagnetic minerals are the dominant magnetic component in Bootle dust samples. Both studied sites show similar magnetic properties, but they can be

Dust control for draglines

Energy Technology Data Exchange (ETDEWEB)

Grad, P.

2009-09-15

Monitoring dust levels inside draglines reveals room for improvement in how filtration systems are used and maintained. The Australian firm BMT conducted a field test program to measure airflow parameters, dust fallout rates and dust concentrations, inside and outside the machine house, on four draglines and one shovel. The study involved computational fluid dynamics (CFD) simulations. The article describes how the tests were made and gives results. It was not possible to say which of the two main filtration systems currently used on Australian draglines - Dynavane or Floseps - performs better. It would appear that more frequent maintenance and cleaning would increase the overall filtration performance and systems could be susceptible to repeat clogging in a short time. 2 figs., 1 photos.

[Effects of simulated acid rain on respiration rate of cropland system with different soil pH].

Science.gov (United States)

Zhu, Xue-zhu; Zhang, Gao-chuan; Li, Hui

2009-10-15

To evaluate the effects of acid rain on the respiration rate of cropland system, an outdoor pot experiment was conducted with paddy soils of pH 5.48 (S1), pH 6.70 (S1) and pH 8.18 (S3) during the 2005-2007 wheat-growing seasons. The cropland system was exposed to acid rain by spraying the wheat foliage and irrigating the soil with simulated rainwater of T1 (pH 6.0), T2 (pH 6.0, ionic concentration was twice as rainwater T1), and T3 (pH 4.4, ionic concentration was twice as rainwater T1), respectively. The static opaque chamber-gas chromatograph method was used to measure CO2 fluxes from cropland system. The results showed that acid rain affected the respiration rate of cropland system through crop plant, and the cropland system could adapt to acid rain. Acid rainwater significantly increased the average respiration rate in alkaline soil (S3) cropland system, while it had no significant effects on the average respiration rate in neutral soil (S2) and acidic soil (S1) cropland systems. During 2005-2006, after the alkaline soil cropland system was treated with rainwater T3, the average respiration rate was 23.6% and 27.6% higher than that of alkaline soil cropland system treated with rainwater T1 and T2, respectively. During March to April, the respiration rate was enhanced with the increase of rainwater ionic concentration, while it was dropped with the decrease of rainwater pH value in acidic soil cropland system. It was demonstrated that soil pH and crop plant played important roles on the respiration rate of cropland system.

Dust-Plasma Interactions

International Nuclear Information System (INIS)

Rosenberg, Marelene

2005-01-01

Our theoretical research on dust-plasma interactions has concentrated on three main areas: (a)studies of grain charging and applications; (b) waves and instabilities in weakly correlated dusty plasma with applications to space and laboratory plasmas; (c) waves in strongly coupled dusty plasmas.

Elemental Concentration of Harmattan Dust Sample in Iwo and Oyo ...

African Journals Online (AJOL)

ADOWIE PERE

According to Balogun (1979), two sources of dust plumes were identified .... metals. Heavy metals are known to be harmful to human health if they are more than the recommended ... Chemical. Characterization and Source Apportionment of.

[Asthma due to grain dust].

Science.gov (United States)

Baur, X; Preisser, A; Wegner, R

2003-06-01

The actual literature as well as two case reports described in detail show that grain dust induces asthmatic reactions and ODTS which are obviously not of allergic origin. For diagnosis occupational-type exposure tests are decisive whereas allergological testing usually is not. Endotoxins which are present in the grain dust samples in high concentrations have to be regarded as the major causative components. To avoid irreversible lung function impairment a comprehensive early diagnosis is necessary. Generally, a remarkable reduction of exposure to dust with high levels of airborne endotoxin in agriculture has to be achieved since in many workplaces corresponding exposures are still rather high.

In vitro toxicology of respirable Montserrat volcanic ash.

Science.gov (United States)

Wilson, M R; Stone, V; Cullen, R T; Searl, A; Maynard, R L; Donaldson, K

2000-11-01

In July 1995 the Soufriere Hills volcano on the island of Montserrat began to erupt. Preliminary reports showed that the ash contained a substantial respirable component and a large percentage of the toxic silica polymorph, cristobalite. In this study the cytotoxicity of three respirable Montserrat volcanic ash (MVA) samples was investigated: M1 from a single explosive event, M2 accumulated ash predominantly derived from pyroclastic flows, and M3 from a single pyroclastic flow. These were compared with the relatively inert dust TiO(2) and the known toxic quartz dust, DQ12. Surface area of the particles was measured with the Brunauer, Emmet, and Teller (BET) adsorption method and cristobalite content of MVA was determined by x ray diffraction (XRD). After exposure to particles, the metabolic competence of the epithelial cell line A549 was assessed to determine cytotoxic effects. The ability of the particles to induce sheep blood erythrocyte haemolysis was used to assess surface reactivity. Treatment with either MVA, quartz, or titanium dioxide decreased A549 epithelial cell metabolic competence as measured by ability to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). On addition of mannitol, the cytotoxic effect was significantly less with M1, quartz, and TiO(2). All MVA samples induced a dose dependent increase in haemolysis, which, although less than the haemolysis induced by quartz, was significantly greater than that induced by TiO(2). Addition of mannitol and superoxide dismutase (SOD) significantly reduced the haemolytic activity only of M1, but not M2 or M3, the samples derived from predominantly pyroclastic flow events. Neither the cristobalite content nor the surface area of the MVA samples correlated with observed in vitro reactivity. A role for reactive oxygen species could only be shown in the cytotoxicity of M1, which was the only sample derived from a purely explosive event. These results suggest that in general the

Particulate matter and polycyclic aromatic hydrocarbons in a selected athletic hall: ambient concentrations, origin and effects on human health

Science.gov (United States)

Kuskowska, Karolina; Rogula-Kozłowska, Wioletta; Rogula-Kopiec, Patrycja

2018-01-01

The paper presents the results of research on the concentration of 16 polycyclic aromatic hydrocarbons (PAHs) associated with total suspended particles (TSP) and their respirable fraction (PM4) in one of the Warsaw sports halls. Samples of dust were collected for 15 days simultaneously inside and outside (atmospheric air) of the sports hall. The obtained data allowed calculating diagnostic ratios indicating the origin of the PAHs and selected indicators of cumulative exposure to the PAH mixture. Both PM and PAH in the surveyed area were derived from the combustion of solid fuels; this involved pollution both in the atmospheric air and in the air inside the sports hall. It has been shown that the exposure of sports hall users to PAHs is significantly higher than the exposure resulting from concentrations recorded in the atmospheric air.

Pinus sylvestris switches respiration substrates under shading but not during drought

Science.gov (United States)

Hartmann, Henrik; Fischer, Sarah; Hanf, Stefan; Frosch, Torsten; Poppp, Jürgen; Trumbore, Susan

2015-04-01

Reduced carbon assimilation during prolonged drought forces trees to rely on stored carbon to maintain vital processes like respiration. It has been shown, however, that the use of carbohydrates, a major carbon storage pool and main respiratory substrate in plants, strongly declines with deceasing plant hydration. Yet, no empirical evidence has been produced to what degree other carbon storage compounds like lipids and proteins may fuel respiration during drought. We exposed young scots pine trees to carbon limitation using either drought or shading and assessed respiratory substrate use by monitoring the respiratory quotient, δ13C of respired CO2and concentrations of the major storage compounds, i.e. carbohydrates (COH), lipids and amino acids. Generally, respiration was dominated by the most abundant substrate. Only shaded trees shifted from carbohydrate-dominated to lipid-dominated respiration and showed progressive carbohydrate depletion. In drought trees respiration was strongly reduced and fueled with carbohydrates from also strongly reduced carbon assimilation. Initial COH content was maintained during drought probably due to reduced COH mobilization and use and the maintained COH content may have prevented lipid catabolism via sugar signaling. Our results suggest that respiratory substrates other than carbohydrates are used under carbohydrate limitation but not during drought. Thus, respiratory substrate change cannot provide an efficient means to counterbalance carbon limitation under natural drought.

Personal exposure versus monitoring station data for respirable particles

Energy Technology Data Exchange (ETDEWEB)

Sega, K; Fugas, M

1982-01-01

Personal exposure to respirable particles of 12 subjects working at the same location, but living in various parts of Zagreb, was monitored for 7 consecutive days and compared with simultaneously obtained data from the outdoor network station nearest to subject's home. Although personal exposure is related to the outdoor pollution, other sources play a considerable role. Indoor exposure takes, on the average, more than 80% of the total time. The ratio between average personal exposure and respirable particle levels in the outdoor air decreases with the increased outdoor concentration (r = -0.93), indicating that this relationship might serve as a basis for a rough estimate of possible personal exposure.

Facepiece leakage and fitting of respirators

International Nuclear Information System (INIS)

White, J.M.

1978-05-01

The ways in which airborne contaminants can penetrate respirators and the factors which affect the fit of respirators are discussed. The fit of the respirator to the face is shown to be the most critical factor affecting the protection achieved by the user. Qualitative and quantitative fit testing techniques are described and their application to industrial respirator programs is examined. Quantitative measurement of the leakage of a respirator while worn can be used to numerically indicate the protection achieved. These numbers, often referred to as protection factors, are sometimes used as the basis for selecting suitable respirators and this practice is reviewed. (author)

Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

Directory of Open Access Journals (Sweden)

Shohei Sakuda

2014-03-01

Full Text Available Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control.

Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

Science.gov (United States)

Sakuda, Shohei; Prabowo, Diyan Febri; Takagi, Keiko; Shiomi, Kazuro; Mori, Mihoko; Ōmura, Satoshi; Nagasawa, Hiromichi

2014-01-01

Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A) inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III) and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control. PMID:24674936

Dust Quantization and Effects on Agriculture Over Uttar Pradesh, India

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