Fifteen year follow-up study of VC and FEV1 in dust-exposed workers

A baseline survey of 3457 male workers exposed to various forms of dust from 11 medical facilities throughout Japan was carried out in 1978 or 1979. We completed the present follow-up study 15 years later on 693 of the men. Vital capacity (VC) and forced expiratory volume in one second (FEV1) were analyzed as indices of lung function. We examined factors that affected both baseline and interval changes in VC and FEV1 by stepwise multiple regression analysis. In the cross-sectional data analysis of baseline, height, profusion rate (PR) and age were selected as predictor variables for VC and FEV1, additionally duration of working for FEV1. It indicated that baseline VC decreased by 84.0 ml with each increase in PR classification. Similarly, baseline FEV1 decreased by 146.6 ml with increasing PR. Baseline VC and FEV1 were both positively influenced by subject height. In the longitudinal analysis, baseline PR, age and smoking habits were selected for predictor variables for decline of VC and FEV1. It indicated a negative influence of baseline PR classification on VC and FEV1 changes (-5.0 and -7.5 ml/y, respectively). Smoking decreased VC and FEV1 by 6.1 and 5.8 ml/y, respectively.