• Roentgenographic evidence of pneumoconiosis was found in 153 coal miners. Sixty of these were free from signs of cardiac disease other than cor pulmonale and returned for study often enough to permit satisfactory follow-up study. Complaints were referable to the chest in 32 cases; in the remaining 28 they chiefly involved other systems. The 60 with pneumoconiosis were compared with a reference group of 74 miners matched as to age but free from roentgenographic signs of pneumoconiosis. The latter group ranged in age from 45 to 76 years, and the average time they had worked underground was 35 years. Physical and roentgenographic examinations were supplemented by laboratory tests. The men who remained free of roentgenographic abnormality showed a lower incidence of lower respiratory infection, emphysema, and dyspnea than did those with the roentgenographic lesions.
Levine MD, Hunter MB. CLINICAL STUDY OF PNEUMOCONIOSIS OF COAL WORKERS IN OHIO RIVER VALLEY. JAMA. 1957;163(1):1–4. doi:10.1001/jama.1957.02970360003001