The influence of smoking habits and body weight on vital capacity and FEV1 in male Air Force personnel: a longitudinal and cross-sectional analysis.

Vital capacity (VC) and forced expiratory volume in one second (FEV1) measured in 7,123 men during annual or biennial medical examination were analyzed as a function of age (A), weight (W), and standing height (H). The subjects were grouped according to their smoking habits. A cross-sectional and longitudinal study was performed. Vital capacity and FEV1 were found to increase with age during the first 22 to 23 yr; thereafter, a steady decline was observed, more pronounced in smokers than in nonsmokers. In both longitudinal and cross-sectional surveys, body weight influenced the values of VC and FEV1. An increase of weight tended to be accompanied by an increase in VC and FEV1 in the younger, taller, and lighter subjects. This effect lessened and even reversed with increasing age and weight, decreasing height, and heavier smoking (in the longitudinal study). The influence of height on VC and FEV1 appeared to depend markedly on the weight of the subjects.