Decreases in 1 second forced expiratory volume (FEV1) and development of mucus hypersecretion in Australian coal miners were examined. FEV1 data on 2807 males working in coal mines in New South Wales, Australia obtained during physical examinations between 30 June 1970 and 30 June 1973 were compared with data obtained between 30 June 1980 and 30 June 1983. The FEV1 data and data on age, height, cumulative current or previous dust exposure, current or previous tobacco use, and alcohol consumption were analyzed by logistic regression techniques. The mean decrease in FEV1 of the subjects over the study period was 0.81 liter. The FEV1 decrement was significantly, positively associated with age, previous dust exposure, previous smoking, and alcohol consumption. A second analysis was performed on 847 male coal miners who were examined at 5 year intervals between 30 June 1970 and 30 June 1985. Data on FEV1, smoking, alcohol use, the presence or absence of chronic mucus hypersecretion, and relative cumulative dust exposure were analyzed by logistic regression techniques. Chronic mucus hypersecretion and FEV1 per height squared (FEV1/h2) were used as dependent variables in the analyses. The extent of chronic mucus hypersecretion and airway obstruction, measured as FEV1/h2, increased over the study period. When controlled for age, chronic mucus hypersecretion was positively, significantly associated with relative dust exposure, smoking, and alcohol consumption. Airway obstruction was significantly positively associated with smoking and weakly associated with relative dust exposure and alcohol consumption. The authors conclude that a clear association between past dust exposure, smoking, and alcohol consumption and development of chronic mucus hypersecretion and airways obstruction has been demonstrated.