Whether certain personal characteristics influence the perception of exposure to dusts, gases or fumes was assessed in 6803 men and 6765 women drawn from nonmanual worker households in seven French cities. Factors modifying the strength of the association between two estimates of exposure (here a job exposure matrix estimate and exposure reported by the subjects) are potential recall determinants of exposure. This association was significantly stronger in men than in women, suggesting a better perception of exposure in men. The strength of the association between both estimates of exposure increased significantly among men according to educational level. Smoking habits had no effect on the perception of exposure. The perception of exposure did not vary significantly according to respiratory symptoms in women. In men, subjects without chronic cough or chronic bronchitis had a significantly higher perception of exposure than the others, but no difference was shown for wheezing, dyspnoea or asthma.