Respirable Dust Samples Research Articles

Identifying sources of respirable quartz and silica dust in underground coal mines in southern West Virginia, western Virginia, and eastern Kentucky

Prior research has suggested that the source of respirable silica dust in underground coal mines is typically the immediate top or bottom lithology adjacent to the mined seam, not mineral matter bound within the mined coal bed. Geochemical analyses were applied in an effort to identify the specific source rock of respirable quartz dust in coal mines. The analyses also demonstrate the compositional changes that take place in the generation of the respirable dust fraction from parent rock material. All six mine sites were mining coal with relatively low mineral matter content, although two mines were operating in the Fire Clay coal bed which contains a persistent tonstein. Interpretations of Ca, Mg, Mn, Na, and K concentrations strongly suggest that the top strata above the mined seam is the primary source of mineral dust produced during mining. One site indicates a mixed or bottom source, possibly due to site specific conditions. Respirable dust compositional analyses suggest a direct relationship between the quantity of mineral Si and the quantity of quartz Si. A similar relationship was not found in either the top or bottom rocks adjacent to the mined seam. An apparent loss of elemental Al was noted in the respirable dust fraction when compared to potential parent rock sources. Elemental Al is present in top and bottom rock strata within illite, kaolinite, feldspar, and chlorite. A possible explanation for loss of Al in the respirable dust samples is the removal of clays and possibly chlorite minerals. It is expected that removal of this portion of the Al bearing mineral matter occurs during rock abrasion and dust transport prior to dust capture on the samplers.

A revised conversion factor relating respirable dust concentrations measured by 10 mm Dorr-Oliver nylon cyclones operated at 1.7 and 2.0 L min−1

Accurate measurement of workplace respirable dust concentration is an essential step in eliminating lung disease in any occupational setting. In the United States (U.S.) coal mining industry, this measurement process has relied upon a personal sampler that includes a 10 mm Dorr-Oliver (DO) nylon cyclone operated at a flow rate of 2.0 L min(-1) to collect a respirable dust sample. Dust concentrations measured with this sampler are multiplied by 1.38, which was empirically derived, to convert them to measurements approximating the United Kingdom British Medical Research Council (BMRC) definition of respirable dust upon which the health effects of coal mine dust are based. The International Organization for Standardization (ISO) subsequently refined the respirable dust definition and the U.S. National Institute for Occupational Safety and Health (NIOSH) 1995 Criteria for a Recommended Standard presented a conversion multiplier of 0.857 to apply to the 2.0 L min(-1) DO (in addition to the1.38 multiplier) to obtain equivalent ISO concentrations, as approximated by the 1.7 L min(-1) DO. However, the conversion multiplier 0.857 was derived indirectly from a limited size distribution data set rather than a direct comparison of the DO samplers. The present analysis focuses on providing a more accurate conversion multiplier derived from direct comparisons of the 2.0 L min(-1) (with 1.38 BMRC equivalency multiplier) and 1.7 L min(-1) DO cyclones. A weighted linear regression analysis of this database suggests that a more accurate estimate of the conversion multiplier is 0.815.

Correlation between Ground Level Ultra-Violet Radiation & Lower Atmospheric Aerosol Load

AbstractUV radiation is known to affect many biological and chemical processes, and is largely detrimental to individual organisms. Specific concerns include increase in the incidence of skin cancer, ocular damage, and other health effects in humans and other animals; damage to terrestrial and oceanic vegetation; changes in the chemistry of the lower atmosphere e.g. photochemical smog formation. Present study was undertaken to monitor lower atmospheric aerosol load with Respirable Dust Sampler and ultraviolet radiation with UV-radiometer in the ambient environment of Delhi. PM10 (< 10 µm) and SPM (> 10 µm) samples collected for the period of the study (8 weeks, 2 samples per week, total 16 samples). Hourly UV Fluxes (UV-B & UV-A) were measured from four hours ahead to four hours following the solar noon (LAT 12:00hrs), alongside aerosol sampling twice in a week. Our study shows, lower-atmospheric load of finer particles (PM10) significantly cut-off both UV-A and UV-B fluxes reaching the earth surface. PM10 load shows a satisfactory negative correlation with UV-A and UV-B fluxes at ground level.

A Survey of Size-Fractionated Dust Levels in the U.S. Wood Processing Industry

A survey of size-fractionated dust exposure was carried out in 10 wood processing plants across the United States as part of a 5-year longitudinal respiratory health study. The facilities included a sawmill, plywood assembly plants, secondary wood milling operations, and factories producing finished wood products such as wood furniture and cabinets. Size-fractionated dust exposures were determined using the RespiCon Personal Particle Sampler. There were 2430 valid sets of respirable, thoracic, and inhalable dust samples collected. Overall, geometric mean (geometric standard deviation) exposure levels were found to be 1.44 (2.67), 0.35 (2.65), and 0.18 (2.54) mg/m, for the inhalable, thoracic, and respirable fractions, respectively. Averaged across all samples, the respirable fraction accounted for 16.7% of the inhalable dust mass, whereas the corresponding figure for thoracic fraction as a percentage of the inhalable fraction was 28.7%. Exposures in the furniture manufacturing plants were significantly higher than those in sawmill and plywood assembly plants, wood milling plants, and cabinet manufacturing plants, whereas the sawmill and plywood assembly plants exhibited significantly lower dust levels than the other industry segments. Among work activities, cleaning with compressed air and sanding processes produced the highest size-fractionated dust exposures, whereas forklift drivers demonstrated the lowest respirable and inhalable dust fractions and shipping processes produced the lowest thoracic dust fraction. Other common work activities such as sawing, milling, and clamping exhibited intermediate exposure levels, but there were significant differences in relative ranking of these across the various industry segments. Processing of hardwood and mixed woods generally were associated with higher exposures than were softwood and plywood, although these results were confounded with industry segment also.

Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira

We measured the quartz content of 20 bulk settled dust and 200 respirable dust samples in a cross-sectional dust exposure assessment that is part of an epidemiological study to ascertain the risk of nonmalignant respiratory diseases among Zambian copper miners. Dust samples were collected from the copper mines of Mopani Copper Mine plc (Mufulira and Nkana Mines). Analytical measurements employed NIOSH Method 0600 for gravimetric analysis of respirable dust and NIOSH Method 7500 for quartz analysis in bulk and respirable dust samples. The measured quartz content of respirable dust showed that 59% and 26% of Mufulira and Nkana Mine samples, respectively, were above the calculated U.S. Occupational Safety and Health Administration permissible exposure limit. The mean intensities of respirable dust exposure at Mufulira and Nkana were 0.992 mg/m3 (range 0-7.674) and 0.868 mg/m3 (range 0-6.944), respectively while the mean intensities of respirable quartz at Mufulira and Nkana were 0.143 mg/m3 (range 0-1.302) and 0.060 mg/m3 (range 0-0.317), respectively. These results indicate weak dust monitoring at these mines which may increase the risk of nonmalignant disease in many miners. Since Zambian mining regulations do not have crystalline silica exposure limits, these results accord with the recommendation that Zambian mining houses and the government establish crystalline silica analysis laboratory capacity and adopt dust mass concentration occupational exposure limits for more protective dust monitoring of workers.

Exposure to fibres, crystalline silica, silicon carbide and sulphur dioxide in the norwegian silicon carbide industry.

Objectives: The aim of this study was to assess personal exposure to fibres, crystalline silica, silicon carbide (SiC) and sulphur dioxide in the Norwegian SiC industry.Methods: Approximately 720 fibre samples, 720 respirable dust samples and 1400 total dust samples were collected from randomly chosen workers from the furnace, processing and maintenance departments in all three Norwegian SiC plants. The respirable dust samples were analysed for quartz, cristobalite and non-fibrous SiC content. Approximately 240 sulphur dioxide samples were collected from workers in the furnace department.Results: The sorting operators from all plants, control room and cleaning operators in Plant A and charger, charger/mix and payloader operators in Plant C had a geometric mean (GM) of fibre exposure above the Norwegian occupational exposure limit (OEL) (0.1 fibre cm−3). The cleaner operators in Plant A had the highest GM exposure to respirable quartz (20 μg m−3). The charger/mix operators in Plant C had the highest GM exposure to respirable cristobalite (38 μg m−3) and the refinery crusher operators in Plant A had the highest GM exposure to non-fibrous SiC (0.65 mg m−3). Exposure to the crystalline silica and non-fibrous SiC was generally low and between 0.4 and 2.1% of the measurements exceeded the OELs. The cleaner operators in Plant A had the highest GM exposure to respirable dust (1.3 mg m−3) and total dust (21 mg m−3). GM exposures for respirable dust above the Norwegian SiC industry-specific OEL of 0.5 mg m−3 were also found for refinery crusher operators in all plants and mix, charger, charger/mix and sorting operators in Plant C. Only 4% of the total dust measurements exceeded the OEL for nuisance dust of (10 mg m−3). Exposure to sulphur dioxide was generally low. However, peaks in the range of 10–100 p.p.m. were observed for control room and crane operators in Plants A and B and for charger and charger/mix operators in Plant C.Conclusion: Workers in the SiC industry are exposed to a mixture of several agents including SiC fibres, quartz, cristobalite, non-fibrous SiC and sulphur dioxide. Exposure levels were generally below the current Norwegian OELs; however, high exposure to fibres and respirable dust still occurs in the furnace department.

Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira

We measured the quartz content of 20 bulk settled dust and 200 respirable dust samples in a cross-sectional dust exposure assessment that is part of an epidemiological study to ascertain the risk of nonmalignant respiratory diseases among Zambian copper miners. Dust samples were collected from the copper mines of Mopani Copper Mine plc (Mufulira and Nkana Mines). Analytical measurements employed NIOSH Method 0600 for gravimetric analysis of respirable dust and NIOSH Method 7500 for quartz analysis in bulk and respirable dust samples. The measured quartz content of respirable dust showed that 59% and 26% of Mufulira and Nkana Mine samples, respectively, were above the calculated U.S. Occupational Safety and Health Administration permissible exposure limit. The mean intensities of respirable dust exposure at Mufulira and Nkana were 0.992 mg/m3 (range 0-7.674) and 0.868 mg/m3 (range 0-6.944), respectively while the mean intensities of respirable quartz at Mufulira and Nkana were 0.143 mg/m3 (range 0-1.302) and 0.060 mg/m3 (range 0-0.317), respectively. These results indicate weak dust monitoring at these mines which may increase the risk of nonmalignant disease in many miners. Since Zambian mining regulations do not have crystalline silica exposure limits, these results accord with the recommendation that Zambian mining houses and the government establish crystalline silica analysis laboratory capacity and adopt dust mass concentration occupational exposure limits for more protective dust monitoring of workers.

Measurement and modeling of respirable particulate (PM10) and lead pollution over Madurai, India

Samples of particulate matter less than or equal to 10 μm (PM10) were collected round the clock duration by using a respirable dust sampler (APM 460 BL) in Madurai, the second largest and most densely populated city of Tamil Nadu, India. The Environmental Protection Agency (EPA)-recommended standard methods were adopted not only for sample collection but also for subsequent analysis of respirable particulate pollutants. The observed PM10 concentrations varied from 88.1 to 226.9 μg/m3, and lead concentrations ranged between 0.21 to 1.18 μg/m3. The annual averages of the concentrations of the pollutants of current concern manifested that they were mostly below the Indian air quality standards and were generally comparable with those concentrations observed in most other Indian urban areas. The AERMOD model was validated simultaneously by comparing the predicted levels with the estimated levels of PM10. The generated database of the present investigation on the degree of pollution may be used for further research investigation and pollution abatement in the city.

Equivalency of a personal dust monitor to the current United States coal mine respirable dust sampler

The United States National Institute for Occupational Safety and Health, through an informal partnership with industry, labor, and the United States Mine Safety and Health Administration, has developed and tested a new instrument known as the Personal Dust Monitor (PDM). The new dust monitor is an integral part of the cap lamp that coal miners normally carry to work and provides continuous information about the concentration of respirable coal mine dust within the breathing zone of that individual. Previous laboratory testing demonstrated that there is a 95% confidence that greater than 95% of individual PDM measurements fall within +/-25% of reference measurements. The work presented in this paper focuses on the relationship between the PDM and respirable dust concentrations currently measured by a coal mine dust personal sampler unit utilizing a 10 mm Dorr-Oliver nylon cyclone. The United Kingdom Mining Research Establishment instrument, used as the basis for coal mine respirable dust standards, had been designed specifically to match the United Kingdom British Medical Research Council (BMRC) criterion. The personal sampler is used with a 1.38 multiplier to convert readings to the BMRC criterion. A stratified random sampling design incorporating a proportionate allocation strategy was used to select a sample of mechanized mining units representative of all US underground coal mines. A sample of 180 mechanized mining units was chosen, representing approximately 20% of the mechanized mining units in production at the time the sample was selected. A total of 129 valid PDM/personal sampler dust sample sets were obtained. A weighted linear regression analysis of this data base shows that, in comparison with the personal sampler, the PDM requires a mass equivalency conversion multiplier of 1.05 [95% C.I.=(1.03, 1.08)] when the small intercept term is removed from the analysis. Removal of the intercept term results in a personal sampler-equivalent concentration increase of 2.9% at a PDM measurement of 2.0 mg m(-3).

Exposure profiles and source identifications for workers exposed to crystalline silica during a municipal waste incinerator relining period

In this study, respirable crystalline silica exposures to furnace relining workers of 7 exposure groups were assessed by conducting personal respirable dust samplings. All possible pollutant sources were identified for each exposure group through field observations, and bulk samples were randomly collected from each identified pollutant source. All collected samples were analyzed for their tridymite, cristobalite, and quartz contents by using the X-ray diffraction method. Results show that quartz was the only detectable crystalline silica content. We found that the resultant respirable quartz exposure levels presented in sequence for the 7 exposure groups (sand blasting > bottom ash cleaning > wall demolishing > relining > others > grid repairing > scaffold establishing) were different from that of the corresponding respirable dust exposure levels (bottom ash cleaning > wall demolishing > sand blasting > relining > grid repairing > scaffold establishing > others). 87.3–100% of workers’ respirable quartz exposures of the 7 exposure groups exceeded the TLV-TWA (0.025 mg m −3) indicating appropriate control strategies should be taken immediately. By comparing the fractions of quartz contained in personal respirable dust samples with that contained in all possible pollutant sources for each exposure group, this study identified main pollutant sources for each exposure group as: bottom ash cleaning and scaffold establishing: bottom ash; sand blasting: blasting sand; wall demolishing: refractory cement + wall ash; wall relining: refractory brick; grid repairing: wall ash + refractory cement; grid repairing: wall ash + refractory cement; others: blasting sand + bottom ash. Finally, effective control strategies were proposed for exposure reduction by using above information together with our field observations.

Airborne Antibiotic Concentrations in a Swine Feeding Operation

During the past 50 years, it has become common practice in the U.S. to add antibiotics to livestock feed to reduce disease and promote growth. Use of antibiotics in this manner has become the source of increasing controversy because overuse of antibiotics is suspected of leading to resistance in bacteria that cause human diseases. The purpose of this study was to measure airborne antibiotic concentrations in a swine production facility that routinely included antibiotics in feed. Samples were collected in a hog facility that included rooms devoted to farrowing, nursery, and growing operations. Analytical methods were developed to measure concentrations of the antibiotics tylosin and lincomycin in air samples. Tylosin was mixed in the feed in some of the rooms in the facility. While lincomycin was not added during this study, it had been used in this facility in the past and therefore was included in the analytical testing. Inhalable (n = 34), respirable (n = 37), and high-volume (n = 16) dust samples were collected on PVC filters over a two-month period. Tylosin concentrations were above the limit of quantification (LOQ) in 93% of the samples, while lincomycin concentrations were above the LOQ in only 9% of the samples (LOQ = 0.04 ng/sample). The average tylosin concentrations were 3, 18, and 49 ng/m3 in the respirable, inhalable, and high-volume samples, respectively. No occupational or environmental worker exposure criteria currently exist for antibiotics in air. The results of this study may be used to estimate potential swine production worker exposures and to further study the association between these exposures and health effects.

Determination and analysis of silica particles surface alumino-silicate occlusion

To investigate the methods of determining aluminum silicate coated on the surface of silica particles and analyze the role of surface occlusion on development of silicosis. Respirable dust samples were collected on filters using 2 L/min flow in tungsten mines and pottery factories of Jiangxi province, and tin mines of Guanxi province. Dust particles were analyzed by a multiple-voltage scanning electron microscopy-energy dispersive X-ray spectroscopy (MVSEM-EDS) using 20 KeV and 5 KeV electron beam accelerating voltages. Changes in the silicon to aluminum X-ray line intensity ratio between the two voltages are compared particle by particle. This provided an index that distinguishes a silica particle that was homogeneously aluminum-contaminated from a clay coated silica particle. The total of 3,982 dust particles from 47 dust samples of seven pottery factories, three tin mines and three tungsten mines were analyzed in this study. Significant difference of aluminum silicate coated on the surface of silica particle was shown between particles from pottery factories and tin mines. The average sample percentage of respirbale-sized silica particles alumino-silicate occlusion in the pottery factories (45%) was higher than that in the tin mines (18%) and tungsten mines (13%). Higher percentages silica particles alumino-silicate occlusion is observed in the pottery factories than that in metal mines. These surface analysis results help to understand differences in risk of silicosis when exposure is normalized to cumulative respirable surface silica dust.

Respirable dust exposure in underground gold miners at Obuasi in Ghana

Mechanised large-scale mining by European companies which began in the Gold Coast (now Ghana) as early as 1877 presently employs approximately 20,000 people. The Obuasi gold mine is one of the world's oldest and richest goldmines producing about eighty percent of Ghana's gold output. The study was conducted to quantify personal exposure to respirable dust and silica for different underground mining occupations in the Obuasi mine. Personal respirable dust samples were taken from a stratified sample of 125 (10%) of the 1229 underground miners available for the study. All filter samples were analysed gravimetrically and 1 in 10 filters analysed for their silica content. The mean shift/daily concentration of the underground respirable dust was 0.83 mg/m 3 (SD ± 0.55) and a range of 0.07 to 2.86 mg/m3 over a mean sampling time of 6 hours. The concentration of respirable silica ranged from 0.01 to 0.12 mg/m 3 ; mean 0.06 mg/m 3 . The mean silica content of the respirable dust was 9.93%. The present study shows a low personal respirable dust exposure levels as well as silica content in the Obuasi gold mines in Ghana. Keywords : respirable dust, crystalline silica, mining, personal air measurements Journal of Science and Technology Vol. 26(1) 2006: 14-21

Variability of Exposure and Estimation of Cumulative Exposure in a Manually Operated Coal Mine

This study aims at estimating variability in exposure to respirable dust and assessing whether the a priori grouping by job team is appropriate for an exposure-response study on respiratory effects among workers in a manually operated coal mine in Tanzania. Furthermore, estimated exposure levels were used to calculate cumulative exposure. Full-shift personal respirable dust samples (n = 204) were collected from 141 randomly chosen workers at underground and surface work sites. The geometric mean exposure for respirable dust varied from 0.07 mg m(-3) for office workers to 1.96 mg m(-3) for the development team. The analogous range of respirable quartz exposure was 0.006-0.073 mg m(-3). Variance components were estimated using random effect models. For most job teams the within-worker variance component was considerably higher than the between-worker variance component. For respirable dust the estimated attenuation of the linear exposure-response relationship was low (5.9%) when grouping by job team. Grouping by job team was considered appropriate for studying the association between current dust exposure and respiratory effects. Based on the estimated worker-specific mean exposure in the job teams, the arithmetic mean cumulative exposure for the 299 workers who participated in the epidemiological part of the study was 38.1 mg* yr m(-3) for respirable dust and 2.0 mg* yr m(-3) for quartz.

Crystalline Silica Analysis: A Comparison of Calibration Materials and Recent Coal Mine Dust Size Distributions

Abstract Since 1982 standard calibration materials recommended for respirable crystalline silica analysis by the Mine Safety and Health Administration (MSHA) P7 Infrared Method and the National Institute for Occupational Safety and Health (NIOSH) X-ray Diffraction (XRD) Analytical Method 7500 have undergone minor changes in size distribution. However, a critical assumption has been made that the crystalline silica in ambient mine atmosphere respirable dust samples has also remained essentially unchanged in particle size distribution. The objective of this work, therefore, is to compare recent particle size distributions of underground coal mine dust and the silica component of these dusts with estimated aerodynamic particle size distributions of calibration standard materials MIN-U-SIL 5, Berkeley 5, and SRM 1878 used by two crystalline silica analysis techniques. This work provides resolution to a previously reported discrepancy involving the proper sample dilution for the particle sizing method used. Dust impactor sampling data for various locations in 13 underground coal mines were collected between 1991 and 1998 and analyzed for the respirable mass median aerodynamic diameters. The data suggest that the MSHA P7 Method will underestimate the silica content of the sample by at most 8.5 % in the median size range of 0.9–3.6 µm and that it is unlikely one would obtain any significant error in the MSHA P7 Method analysis when the method uses Berkeley 5, MIN-U-SIL 5, or SRM 1878 as a calibration standard material. The results suggest that the NIOSH Analytical Method 7500 would be more appropriate for a dust sample that is representative of the total (no cyclone classifier) rather than the respirable airborne dust, particularly since the mass fraction in the size range below 4 µm is usually a small percentage of the total airborne dust mass. However, the NIOSH Analytical Method 7500 is likely to underestimate the silica content of an airborne respirable dust sample by only 5–10%. The results of this study also suggest that any changes that may have occurred in the median respirable size of airborne coal mine dust are not significant enough to cause any appreciable error in the current methods used for respirable crystalline silica analysis.

High Exposure to Respirable Dust and Quartz in a Labour-intensive Coal Mine in Tanzania

Labour-intensive mines are numerous in several developing countries, but dust exposure in such mines has not been adequately characterized. The aim of this study was to identify and quantify the determinants of respirable dust and quartz exposure among underground coal mine workers in Tanzania. Personal respirable dust samples (n = 134) were collected from 90 underground workers in June-August 2003 and July-August 2004. The development team had higher exposure to respirable dust and quartz (geometric means 1.80 and 0.073 mg m(-3), respectively) than the mining team (0.47 and 0.013 mg m(-3)), the underground transport team (0.14 and 0.006 mg m(-3)) and the underground maintenance team (0.58 and 0.016 mg m(-3)). The percentages of samples above the threshold limit values (TLVs) of 0.9 mg m(-3) for respirable bituminous coal dust and 0.05 mg m(-3) for respirable quartz, respectively, were higher in the development team (55 and 47%) than in the mining team (20 and 9%). No sample for the underground transport team exceeded the TLV. Drilling in the development was the work task associated with the highest exposure to respirable dust and quartz (17.37 and 0.611 mg m(-3), respectively). Exposure models were constructed using multiple regression model analysis, with log-transformed data on either respirable dust or quartz as the dependent variable and tasks performed as the independent variables. The models for the development section showed that blasting and pneumatic drilling times were major determinants of respirable dust and quartz, explaining 45.2 and 40.7% of the variance, respectively. In the mining team, only blasting significantly determined respirable dust. Immediate actions for improvements are suggested to include implementing effective dust control together with improved training and education programmes for the workers. Dust and quartz in this underground mine should be controlled by giving priority to workers performing drilling and blasting in the development sections of the mine.

Agricultural Dust Production in Standard and Conservation Tillage Systems in the San Joaquin Valley

The negative health effects of repeated dust exposure have been well documented. In California's San Joaquin Valley, agricultural operations may contribute substantially to airborne particulates. We evaluated four management systems to assess impacts on dust production and soil properties for a cotton (Gossypium hirsutum L.)-tomato (Lycopersicon esculentum Mill.) rotation: standard tillage with (STCC) and without (STNO) cover crop, and conservation tillage with (CTCC) and without (CTNO) cover crop. Gravimetric analysis of total dust (TD, <100-mum aerodynamic diameter) and respirable dust (RD, 4-mum aerodynamic diameter) samples collected in the plume generated by field implements showed that dust concentrations for CTNO treatments were about one-third of their STNO counterparts for both cumulative TD and RD measured throughout the two-year rotation, primarily due to fewer in-field operations. The TD and RD production for STNO and STCC was comparable, whereas the CTCC system produced about twice as much TD and RD as CTNO. Energy dispersive spectroscopy (EDS) analyses showed absolute increases of 8 and 39% organic fragments in STCC and CTCC over STNO and CTNO, respectively, while organic fragments in the TD increased by 6% in both cover crop treatments. Soil C content was positively correlated with clay content and increased by an average of 0.12 and 0.07% in the cover crop and non-cover crop treatments, respectively, although soil C for each treatment showed a distinct response to a field texture gradient. While dust emissions show an immediate decrease due to fewer field operations for the conservation tillage treatments, long-term sampling is necessary to determine the effects that increased aggregation through organic matter additions may have on dust production.

Infrared Analysis of Respirable Coal Mine Dust for Quartz: Thirty-Five Years

Abstract The Mine Safety and Health Administration (MSHA) analyzes respirable coal mine dust samples for quartz content using infrared spectrometry. Samples are low-temperature ashed in an oxygen plasma, suspended in isopropanol, and redeposited onto a vinyl/acrylic copolymer filter for analysis using a Fourier transform infrared spectrometer. The on-filter infrared method was developed by the United States Bureau of Mines and collaboratively tested by Stanford Research Institute (SRI) under contract to the National Institute for Occupational Safety and Health and the Bureau of Mines. The results of the collaborative study were published in 1983. Although much work has been performed since then to improve the precision of the method, details of those improvements have not always been published. Standard methods often do not discuss analytical theory and the preliminary steps necessary to achieve precise results. This paper gives a brief background of the changes that have been made in the procedures used for the analysis of respirable coal mine dust samples for quartz and discusses the current procedures used by MSHA to analyze such samples. Factors affecting the analysis such as optimization of the deposit size of the ashed sample, the importance of centering the sample in the infrared beam, baseline selection points, and peak measurement techniques, as well as the quality assurance procedure and the precision of the analysis, are discussed.

An EP-SAW for measurements of particulate matter in ambient air

In this article we demonstrate the feasibility of combining the two proven technologies of electrostatic precipitators (EP) and surface acoustic wave devices (SAW) for real time applications in particulate monitoring. A plastic cyclone (Higgins–Dewell), used for personal respirable dust sampling, has been modified to include an ionizing source and a Rayleigh SAW device with biased collection plate in place of the usual filter. The flow rate of the air through the cyclone allows size selectivity of particulate matter and we present data showing the effect of the collection plate bias of the collection efficiency.

Statistical Comparison of Diesel Particulate Matter Measurement Methods

Four methods are used to quantify diesel particulate matter (DPM) in the mine environment: respirable combustible dust sampling (RCD), size selective sampling with gravimetric analysis (SSG), respirable dust sampling with elemental carbon (EC) analysis, and respirable dust sampling with total carbon (TC) analysis. The authors assembled data from three underground mine studies to statistically compare these methods. The sampling protocol used in each study was similar. For all the four methods, samples were collected in triplicate at three locations—upwind and downwind of the diesel scoop and on the scoop. The methods were compared with respect to their precision, selectivity, sensitivity, and LOD, as well as their limitations in measuring DPM concentrations. This constitutes a meta-analysis of the available data and provides information over a broader range of mining conditions and DPM concentrations than any of the individual studies. The weighing imprecision for the SSG method is almost twice that for the RCD technique. The imprecision of the EC and TC methods are a function of the mass loading, and EC has a lower imprecision than TC. The EC method was used as the reference “gold standard” against which the other methods were evaluated. The RCD, SSG, and TC methods exhibited substantial levels of interference, leading to much higher minimum concentrations that can be measured by these methods. Of the three, the SSG method has the highest level of interference, primarily from nondiesel material that is collected in the <0.8 µm size range.