A study was conducted of 259 miners in five salt mines to determine possible associations between increased prevalence of respiratory symptoms or reduced pulmonary function with diesel exposure. Two of the mines used diesel powered equipment extensively. All underground jobs were grouped as diesel exposed while all above ground jobs were grouped as nonexposed. Of the remaining three mines, two made minor use of diesel equipment, and one had no diesel powered equipment at all. Workers were classified into high, intermediate, and low exposure groups based on level of diesel exposure. Previously calculated cumulative exposures to respirable particulate and nitrogen-dioxide (10102440) were used to show exposure variations among the worker exposure groups. Examinations of each worker involved a respiratory questionnaire, chest X-ray, and spirometry. Respiratory symptoms included cough, phlegm, and dypsnea. Of the various symptoms, only phlegm showed a statistically significant association with diesel exposure. Diesel exposure was a statistically significant predictor variable for forced vital capacity. Persons with symptoms were found to spend a higher proportion of their time in diesel jobs than persons with no or mild symptoms. Even though persons with symptoms tended to have lower pulmonary function compared to those without symptoms, there were no statistically significant differences in pulmonary function. The strength of association, consistency and biological gradient, and biological plausibility were discussed in context with the results of the study as well as previously published findings. The authors note from personal experience gained during the study that there is irritation upon exposure to diesel fumes. While no evidence has been found of nonmalignant respiratory disease in the study population, the authors suggest that there should be limits based on physical irritation as well as on physical impairment.