Data from the French PAARC (Pollution Atmosphérique et Affections Respiratoires Chroniques) study were used to assess the effect of a priori moderate occupational exposure to dust, gases or chemical fumes on the prevalence of respiratory symptoms and ventilatory function. In this community-based population, without households 'headed' by manual workers, 34% of the 8692 men and 23% of the 7772 women, 25-59 years of age, ever occupationally active, reported some exposure. The studied relationships were adjusted for age, height, smoking habits, socio-occupational class, education and air pollution by logistic or linear regression methods. For men and women, some 50% increase (p less than 0.01) in chronic cough, chronic bronchitis, dyspnoea grade 2 and wheezing prevalence was observed in the exposed group compared to the never exposed, with the strongest association for wheezing. FEV1 and FEF25-75% were not associated with occupational exposure. Among men, FEV1/FVC and FEF25-75%/FVC were significantly lower (p less than 0.001 and p less than 0.05) among the exposed compared to never exposed, but FVC was significantly greater (p less than 0.05). Among women, occupational exposure was significantly related to a lower FEV1/FVC in the subgroup with a history of asthma or wheezing. Results suggest that occupational exposures of relatively low intensity, encountered in the non-industrial work places may constitute a non-negligible risk for respiratory health.