Objectives: The health effects of occupational exposure to silica dust include silicosis and an increased risk of lung cancer. This study estimates the effect of regional location on coal mine employee exposure to crystalline silica, and the odds of a coal workers pneumoconiosis diagnosis.

Study Design: The MSHA datasets cover all enforcement cases from 1970 to present, and include employee personal sampling results for respirable silica dust. The EIA coal production datasets cover from 1949 to present and include coal tonnage by type and mine location.

Methods: The SAS 9.4 statistical program was used in analysis. Descriptive statistics, analysis of covariance, and logistic regression were used to test the effect of region (Appalachian or Rocky Mountains) on coal miner incidence of CWP and silicosis.

Results: The ANACOVA model results were significant [F (5, 25683) = 205.9, p < 0.0001]. The mining region had a statistically significant (p < 0.0001) effect of approximately 1.1 mg/m3 greater silica exposure in an Appalachian Region coal mine versus an Rocky Mountains Region coal mine. In addition, log10 [coal production], respirator use, and coal mining facility type were statistically significant adjustments to the model. The overall logistic regression model results were significant [X2 (5, 24695) = 126.4, p < 0.0001]. Region of mine (Appalachian or Rocky Mountains) was statistically significant (p < 0.0001) with increased odds of CWP for employees working in the Appalachian mines (OR = 2.75, CI: 2.16, 3.56). In addition, log10 [respirable silica personal sample], respirator use, MSHA violation, and year were statistically significant adjustments to the model. Conclusions: The Appalachian mountain region coal miners had significantly higher exposure to silica, and significantly greater odds of CWP.