The association of occupational exposure with respiratory disease and lung function was examined in a cross-sectional study of 1805 aluminum potroom workers. Work-related asthmatic symptoms occurred in 15% of the workers with an exposure of 10 years or more and in 8% of the workers who had been employed less than five years. In a multiple logistic regression analysis an odds ratio (OR) of 3.4 [95% confidence interval (95% CI) 2.1-5.8] for work-related asthmatic symptoms was estimated for long versus short duration of employment. Airflow limitation was also significantly related to years of exposure (OR 2.6, 95% CI 1.7-3.9). Current occupational exposure and the occurrence of respiratory symptoms were not significantly associated. The results suggest that exposure to air pollutants in the primary aluminum industry may lead to the development of asthmatic symptoms, as well as to reduced respiratory function.