Maximal Expiratory Flows in Coal Miners1–3

From a group of approximately 9,000 working coal miners studied by the U. S. Public Health Service in 1973 and 1974, 4 groups of 428 age- and height-matched subjects were selected according to their smoking habits and according to whether or not they had bronchitis. Flow-volume curves, lung volumes, and the more commonly used indices of ventilatory capacity, the forced vital capacity and the forced expiratory volume in 1 sec, had been measured previously in each subject. A larger total lung capacity was observed in smoking than in nonsmoking miners, whether bronchitic or not. This phenomenon is believed to indicate a loss of retractive forces due to destruction of the lung parenchyma associated with cigarette smoking. No comparable change in total lung capacity was observed in the nonsmoking miners with bronchitis. Because dust-induced bronchitis in nonsmoking miners is associated with a decrease in flows at high lung volumes in the absence of an increase in total lung capacity, it is inferred that indust...