Pulmonary function was assessed by spirometry and maximum expiratory flow volume curves to determine whether exposure to an occupational environment contaminated with vinyl chloride (VC) fumes and poly (vinyl chloride) (PVC) dust is associated with an increased risk of respiratory impairment. Data were analyzed for smoking, duration of exposure, and age. The high prevalence of impaired flow (57.5%) could not be attributed to smoking. Prevalence in nonsmokers was 36.4% when exposure was less than 10 yr, 42% when exposure was between 10 and 20 yr, and 80% when exposure exceeded 20 yr. The last is virtually the same rate as for smokers exposed more than 20 yr. The same trend is shown with increasing age. Unlike younger workers, when smokers and nonsmokers ≥ 40 yr of age are compared, prevalence rates of air flow impairment are not statistically different. The present investigation is one of the few in which the effects of occupational exposure could be separated from and were found to predominate over the effects of smoking.