Th prevalence of coal workers' pneumoconiosis.
D003032:Coal Mining; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology*; D010414:Pennsylvania; D011009:Pneumoconiosis / Q000453:epidemiology*; D011658:Pulmonary Fibrosis / Q000453:epidemiology; D012189:Retrospective Studies; D014903:West Virginia