Airways Obstruction From Asbestos Exposure: Ex-smokers
For current smokers all comparisons of pulmonary function tests as differences from predicted for asbestos exposed vs never exposed were significant, including FVC (middle section of Table 3). Thus, comparison of differences in smokers with asbestosis to differences in those never exposed to asbestos were significant for the same parameters as were the* comparisons as percent predicted (middle section, Table 4). Comparison of those with asbestosis to the asbestos-exposed group showed that only one comparison, that of FEF75-85, was not significantly different. It was significant in the percent predicted comparison (middle section, Table 5).
Ex-smokers resembled current smokers, except that asbestosis and asbestos exposure did not differ for terminal flow (FEF75.85) and RV/TLC and FEVi/ FVC approached significance (Table 2, lower block). In ex-smokers, when asbestos-exposed men were compared with unexposed men, differences in means for FEVi, midflow, terminal flow, and TLC were significant (Table 2). When they were compared by mean residual difference from predicted, terminal flow was not significant (lower section of Table 3). When men with asbestosis were compared with those never exposed to asbestos, all differences were significant except for terminal flows, a small difference from the percent predicted comparisons (lower section of Table 4). Comparison of men with asbestosis to those exposed to asbestos without radiographic signs showed that the midflow differences were not quite significant; but otherwise the lower section of Table 5 duplicated the differences shown by percent predicted comparison in the lower section of Table 1. ventolin inhaler
The effects of cigarette smoking on pulmonary function tests were first examined by comparing the smoking groups within the asbestos exposure categories in Table 2. Values for never smokers and current smokers without asbestos exposure (column A) were not significantly different, which confirmed adjustment for the effects of smoking. In contrast, current smokers and ex-smokers with asbestos exposure (column B) showed greater reductions in flows, in FEVi, and in FVC and greater increases in TLC than did never-smokers. Similarly, current and ex-smokers with asbestosis (column C) showed significantly lower flows, FEVi, and FVC and larger TLCs than did never-smokers. Thus, cigarette smoking and asbestos had synergistic effects on pulmonary flows and volumes.