Pulmonary function in normal non-smoking black southern African adults.

Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory ratio (FEV1/FVC x 100) and forced mid-expiratory flow between 25% and 75% of FVC (FMF) were measured in 3000 lifelong non-smoking Xhosa black Southern African adult population aged 20-60 yr from Umtata in the Transkei in Southern Africa. FVC, FEV1 and FMF were highly correlated with each other and all were highly correlated with age and standing height. The normal ranges for spirometric measurements were narrower than in many previous studies. Mean FVC in the present study was 13% higher than predicted values from other African adults. The present study is the most recent and the largest study of black Africans using the American Thoracic Society 1987 selection criteria of pulmonary function curves and can be used as a reference value for mainly Xhosa black Southern African adult population.