Abstract
A group of 39 firefighters was examined during routine firefighing duty. Following smoke exposure the average decrease in one-second forced expiratory volume (FEV1.0) was 0.05 litre (137 observations). This decline in FEV1.0 was related to the severity of smoke exposure as estimated by the firefighter and to the measured particulate concentration of the smoke to which he was exposed. Decreases in FEV1.0 in excess of 0.10 litre were recorded in 30% of observations. Changes in FEV1.0 resulting from a second exposure to smoke on the same tour of duty were greater when smoke exposure at the previous fire was heavy. The repeated episodes of irritation of the bronchial tree that have been documented in this investigation may explain the origin of the previously observed chronic effect of firefighting on respiratory symptoms and pulmonary function.