Pulmonary disease due to organic and inorganic dust inhalation represents a significant health problem in the agricultural community. In response to concern over the potential adverse health effects of agricultural exposures, and to address the question of whether the specific crop worked was associated with decreased lung function, we conducted a cross-sectional survey of pulmonary function in a population of 238 grape workers, 355 tomato workers, and 166 citrus workers in California's Central Valley. In addition, 92 workers (66 males and 26 females) performed spirometry before and after an 8-h work shift. Multiple regression analysis of pulmonary function in all 759 workers revealed that age, height, and smoking-adjusted mean preshift FVC was lower in grape workers than in citrus workers in each of three sex and age groups studied: decreased 314 ml for males greater than or equal to 25 yr of age p less than 0.05, 82 ml for males less than 25 yr, and 83 ml for females greater than or equal to 20 yr. Mean adjusted preshift FVC was also lower in grape workers than tomato workers (decreased 249 ml in males greater than or equal to 25 yr [p less than 0.05], 51 ml for males less than 25 yr, and 46 ml for females greater than or equal to 20 yr). Adjusted mean FEV1 was not different by crop, but FEV1/FVC and forced-expiratory flow from 25 to 75% of the FVC (FEF25-75) were significantly elevated in grape workers of the three age and sex groups compared with citrus or tomato workers.(ABSTRACT TRUNCATED AT 250 WORDS)