The results of pulmonary function tests (PFTs) given to those inhabitants in the western part of Kanagawa Prefecture who visited our hospital for medical examinations between April 1991 and March 1992 were studied comparatively, with their occupation, age, sex, environmental factors and smoking habits taken into account. For this purpose, the subjects totaling 1, 322 were classified into three groups-those who live in the hilly area, those who live in the suburban area and those who live in the coastal area. In the present study, the results of the four PFT items-FVC, FEV 1.0%, FVC and FEV 1.0%-were checked. Careful examination brought into relief the startling fact that many aged people, non-farmers and nonsmokers in the suburban subject group have impaired pulmonary function. It is said that because of the Tokyo-Nagoya expressway and many other motorways, the air in the suburban area is fouled up with exhaust gas to a greater extent than in the other two areas. Although our finding alone could not identify the cause of impaired pulmonary function definitely, air pollution was thought to be a culprit. Further investigation should be made into the living conditions of the examinees. Moreover, environmental monitoring and data analysis have to be carried out in the future.