Respirable-dust levels in coal, metal, and nonmetal mines. Information Circular/1987

The objectives of this report are to describe the current contents of Mine Inspection Data Analysis System (MIDAS), to report analyses of coal and noncoal mine respirable-dust samples collected by Mine Health and Safety Administration (MSHA) inspectors, and to evaluate the proposed change in the metal and nonmetal respirable dust standard from a formula based upon the percentage of quartz identified in the sample to 100 micrograms/cu m of respirable quartz. Based on samples collected by MSHA inspectors, changing the noncoal respirable-dust standard would result in 4% fewer samples with dust concentrations exceeding the standard. Analysis of respirable-coal-dust data collected by MSHA inspectors showed that mines with longwall plows or shears had the highest geometric mean concentrations (1.64 and 1.29mg/cu m, respectively). Mine operations using continuous rippers outnumbered longwall mine operations about 10 to 1 and had a geometric mean concentration of 0.66 mg/cu m.