Fifty-two males and 1 female, who were 19 to 62 y of age (median = 26), were employed at an eastern Quebec peat moss plant and were included in this study. Of these 53 workers, 29 were smokers, 5 were ex-smokers, and 19 had never smoked. The workers were divided by level of exposure into 4 groups: (1) group 1--minimal exposure (N = 7); (2) group 2--light exposure (N = 7); (3) group 3--moderate exposure (N = 17); and (4) group 4--heavy exposure (N = 22). Chest radiographs and physical examinations were normal for all subjects. Only 1 subject had precipitins to Penicillium and Monocillium species isolated from the peat moss plant. Pulmonary function tests were normal and similar in all groups. Thirty-three subjects (20 smokers, 4 ex-smokers, and 9 nonsmokers) had chronic bronchitis; these symptoms were related to work exposure for 28 subjects. Bronchial responsiveness to methacholine was measured in 14 subjects who had persistent cough and sputum. No subject had evidence of airway hyper-responsiveness, i.e., PC20 metacholine less than 8 mg/ml. We concluded that the peat moss workers in our study showed no evidence of extrinsic allergic alveolitis; however, chronic exposure to organic dust leads to chronic cough and sputum production, which is not associated with significant lung impairment nor increase in nonspecific airway responsiveness.