Indices of ventilatory measurements.

Single breath pulmonary function tests of the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) type require adjustments for age and height before the extent of their deviation from normal standards can be assessed. Many regression equations have been proposed in the literature. The Committee on Rating of Mental and Physical Impairment (1965) has provided tables of normal values of FEV1 and FVC for adults by sex, age, and height. These recommended standards were adapted from a study in the United States (Kory, Callahan, Boren, and Syner, 1961). Subsequently, a multiple regression equation was derived from the pooled results of four international studies (including the work of Kory and his co-workers) to predict FEV1 values in white Caucasian males (Cotes, Rossiter, Higgins, and Gilson, 1966). In epidemiological investigations it is sometimes necessary to estimate the extent of impairment in lung function for groups of persons exposed to certain occupational hazards, in relation to their smoking habits, age, and the presence or absence of respiratory symptoms. An extensive study of the aetiology, prevalence, and progression of respiratory disability among men employed in the steel industry in South Wales was recently conducted (Lowe et al., 1968). Regression equations were published which were derived from observations on 8,106