Blood gases in simple coal workers' pneumoconiosis.

Pulmonary gas exchange was measured at rest and during exercise in 30 normal males (14 smokers) and 43 coal workers free of obstructive syndrome, at three levels of oxygenation: hypoxia, normoxia and hyperoxia. The main results are the following: a) in normoxia PaO2 and (A--a)DO2 are slightly abnormal in coal workers at rest and during exercise; b) in hyperoxia (A--a)DO2 and venous admixture are higher in the miners at rest but not during exercise; c) in hypoxia (A--a)DO2 and DLO2 are abnormal in miners as compared with the control subjects; during exercise there is however no difference between the miners and the smokers of the control subjects; d) there is a correlation between PaO2 and (A--a)DO2 during exercise in normoxia and the various diffusion indices; e) (a--A)DCO2 and VD/VT show relatively slight increases in the miners; f) there are several differences between the miners with pin-head images and those with micronodular ones; g) at rest, (a--A)DCO2 and VD/VT are influenced by the degree of oxygenation. These various findings are discussed.