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This study estimated the ratio of the tracheo-bronchial dust fraction to the fraction collected by a respirable dust sampler for a variety of job classifications found in conventional, continuous, and longwall coal mining sections. The ratios could then be applied in epidemiologic studies to existing respirable dust measurements to estimate thoracic mass concentrations for evaluation of the relative importance of the respirable and thoracic dust fractions to obstructive lung disease. Data collected include particle size distributions from four U.S. underground coal mines using eight-stage personal cascade impactors. A total of 180 samples were examined by mine, occupation and occupations grouped by proximity to the mine face, and by mining technology. Several fractions--that collected by the 10-mm nylon cyclone, the American Conference of Governmental Industrial Hygienists respirable and thoracic particulate mass fractions, and the estimated alveolar and tracheo-bronchial deposition fractions--were estimated. These were not significantly different when grouped by occupation, by proximity of work to the mine face, or by the type of mining technology in use. Distributions from one mine varied from the others, perhaps because it used diesel equipment in the haulage ways, which contributed to the fine aerosol fractions. Results suggest that although the tracheo-bronchial dust fraction may contribute to the development of obstructive lung disease, occupation-specific tracheo-bronchial dust fractions are not likely to produce stronger exposure-response estimates than the historically collected respirable dust concentrations.

An evaluation of soil quality, which integrates biological, chemical and physical processes, would be beneficial to regulators as well as mining companies when making reclamation decisions. Coal mining regulations require that industry perform soil sampling and submit laboratory results in order to determine pre-mine and reclaimed soil quality. A rapid and accurate biological soil quality method, such as one-day CO2 (1-day CO2) analysis, can be used to determine soil microbial activity which is related to the soils' ability to sustain nutrient cycling. Our objective in this study was to compare native and reclaimed soils from surface-mine operations in order to assess the effectiveness of the 1-day CO2 method as a tool for determining biological soil quality. Soil samples were taken from sites that visually had poor and well-vegetated reclaimed areas of a surface-mine operation as well as an undisturbed native site. Chemical, physical and biological indicators were compared to 1-day CO2 analysis for microbial activity. Results indicate that the biological soil quality indicators as summarized by 1-day CO2 analysis are a more sensitive indicator of soil health on the reclaimed soils tested than chemical analysis alone. One-day CO2 analysis can be a useful additional tool for regulators and mining companies when assessing the soils ability to sustain plant growth and evaluate reclamation success. [ABSTRACT FROM AUTHOR]