Bronchial responsiveness decreases in relocated aluminum potroom workers compared with workers who continue their potroom exposure

We have compared the bronchial responsiveness (BR) of 12 aluminum potroom workers (index group) who were relocated due to work-related asthmatic symptoms (WASTH) and 26 subjects (reference group) with WASTH who continued to work in pot-rooms. The subjects were examined at regular intervals during a 2-year follow-up period. BR was expressed as the log-transformed dose-response slope [Ln (DRS + 0.5)]. The monthly change in BR (ΔBR) in the index group was −4.87 × 10−2 compared with −1.58 × 10−2 in the reference group. After adjustment for potential confounders, the difference between the index group and the reference group was −2.39 × 10−2 (95% CI: −4.07 × 10−2 to −0.71 × 10−2), i.e. 49% of the decrease in BR in the index group could be explained by the removal from exposure. No improvement in lung function was found in the index group compared with the reference group. The results indicate that the removal of potroom workers from exposure causes a decrease in BR.