Abstract
A study of dust exposures at United States (US) surface coal mines during 1982 and 1983 was conducted. The purpose of the study was to estimate the concentrations of respirable dust and quartz (14808607) dust at US surface coal mines in order to identify jobs having potentially high risks of pneumoconiosis. All data on respirable dust and quartz collected during 1982 and 1983 by US Mine Safety and Health Administration (MSHA) inspectors and surface coal mine operators were reviewed. The standard British Mining Research Establishment (MRE) correction factors were applied to the respirable dust data. The corrected data were analyzed in terms of 35 nonadministrative job categories. The average quartz and MRE corrected respirable dust concentrations for 1409 samples from 627 mines were 0.13 and 1.9mg/m3, respectively. The average corrected respirable dust concentration from 17884 MSHA inspector samples obtained from 2964 mines was 0.6mg/m3. Average quartz concentrations were highest for coal, rock, and highwall drill operators, ranging from 0.34 to 0.49mg/m3. The average quartz exposure for bulldozer operators was 0.18mg/m3. For most other jobs, quartz and respirable dust concentrations averaged less than NIOSH has concluded that the risk of silicosis is negligible for quartz exposures less than 0.5mg/m3, drillers and bulldozers at US surface coal mines may have had an elevated risk for silicosis in 1982 and 1983. Definite conclusions about the extent of pneumoconiosis risk in the US surface coal mining industry cannot be drawn from the MSHA data, however, because it is not known whether the MSHA samples provide a representative estimate of the annual quartz exposure. A larger number of quartz samples for surface coal miners, especially drillers and bulldozer operators, are needed.
