Hyperinflation of the lungs in coal miners.

The residual volume and total lung capacity of 1,455 working Pennsylvania coal miners were determined as part of a larger epidemiological study. The age of the subjects varied between 18 and 65 with a mean of 48-7 years. The total lung capacity of the subjects was determined from standard posteroanterior and lateral chest films while the forced vital capacity was determined by spirometry (O'Shea et al., 1970). The effect of increasing radiographic category of simple coal workers' pneumoconiosis on lung volumes was investigated. It was shown that the residual volume increased with radiographic category and that this occurred whether or not the miners had obstructive airways disease. The presence of obstruction had an additional effect over and above that due to coal dust alone, so that the largest increase in residual volume was found in miners who had both obstruction and radiographic evidence of simple coal workers'