Tests of small airway function in black smokers and nonsmokers.

Tests of small airway function (closing volume, forced expiratory flow in the middle half of the vital capacity, specific airway conductance, and peak expiratory flow) and routine spirometric tests (forced vital capacity, forced expiratory volume in one second, and residual volume) were performed in 848 adult black subjects of both sexes. The group included 422 smokers and 426 nonsmokers. No significant difference was found between smokers and nonsmokers for any of the tests, although some values were higher for men than for women. These findings suggest that reported abnormalities in small airway function in smokers in the general population may not be applicable to black smokers. This may be an important finding in ethnic variability in the incidence of chronic obstructive pulmonary disease.