The association of asthma with occupational exposures was studied in 14,151 adults, aged 25-59 years, from the general population of the 1975 French Pollution Atmospherique et Affections Respiratoires Chroniques (PAARC) Survey. Associations of asthma with specific jobs, such as personal care workers, waiters, and stock clerks, were observed, with age-, sex-, and smoking-adjusted odds ratios between 1.5 and 1.7. Exposures to 18 asthmagenic agents (low and high molecular weight and mixed environment) were estimated by an asthma-specific job exposure matrix. Risks associated with asthma increased when subjects with imprecise estimates of exposure were excluded. Risks increased further with increasing specificity of the definition of asthma when considering jobs or specific agents, such as industrial cleaning agents, latex, flour, highly reactive chemicals, and textiles. For example, for industrial cleaning agents, odds ratios increased from 1.55 (95% confidence interval (CI): 1.08, 2.23) for "ever asthma," to 2.17 (95% CI: 1.41, 3.34) for asthma onset after age 14 years, to 2.35 (95% CI: 1.38, 4.00) for asthma onset after beginning current job, and to 2.51 (95% CI: 1.33, 4.75) for asthma with airflow limitation. Results underlined the importance of the specificity of exposure and asthma definitions and indicated a deleterious role of occupational exposure on asthma, especially for cleaning agents.