Lung function screening in industry.

Regression equations for forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) for 518 black factory workers on the Transvaal highveld were calculated from data obtained during routine lung function testing at an asbestos-cement factory. Only those subjects with clinically and radiologically normal lungs were accepted for the study. The lung capacities of the 60% who were light smokers were not significantly affected. Years of dust exposure were included as a separate independent variable and its contributory effect, after age had been allowed for, was insignificant. The final combined regression equations are considered to be representative of healthy black men on the Transvaal highveld. The values of FVC calculated from these equations were compared with values derived by other authors and, in view of the differences found, it was concluded that predicted values for black workers derived from regression equations for white subjects should not be used for industrial screening purposes. Group-specific equations should be followed when using lung function testing for definitive clinical diagnosis or academic research. The equations suggested for black South African men are FVC = 0.055 (height in cm) - 0.016 (age in years) - 4.502 and FEV1 = 0.043 (height) - 00023 (age) - 3.006.