Respiratory status of surface coal miners in the United States.

The United States Public Health Service examined 1,438 surface coal miners to determine the prevalence of coal worker's pneumoconiosis (CWP), chronic bronchitis, and ventilatory impairment among them. Four percent (fifty-nine individuals) showed some roentgenographic evidence of pneumoconiosis, but only seven miners had films interpreted as CWP of category 2 or greater (according to the UICC/Cincinnati classification system). Moreover, most of the affected miners had worked in underground coal mines for prolonged periods.