Ventilatory function of progressive massive fibrosis among bituminous coal miners in Taiwan

Geographic and ethnic differences exist for the effects of respirable coal-mine dust on the lung function of miners. In this study, the authors compared 177 coal workers who had radiological evidence of progressive massive fibrosis (PMF) with 87 healthy male control subjects. The authors performed maximal expiratory flow volume measurements, single-breath carbon monoxide diffusing capacity (DLco) measurements, and arterial blood gas analysis on each subject. The data revealed that miners with early PMF (category A) had significantly reduced, but well-preserved, vital capacity (VC) and forced expiratory volume in 1 sec (FEV1.0), whereas FEV1.0/VC and DLco were decreased in both nonsmokers and smokers. Abnormally low (i.e., < 80% of predicted values) VC and FEV1.0, and further decreases in DLco, were observed in miners with late PMF (categories B and C). The predominant impairment patterns for workers in categories A, B, and C were obstructive, obstructive and mixed, and mixed and restrictive, respectively. Smoking increased the magnitude of airway obstruction. The authors concluded that diversity in functional impairment was present among bituminous coal miners, even among those with PMF.