The Occupational Health Department of the French Institute for Public Health Surveillance has established and coordinates a program to develop job-exposure matrices tailored to the general French population (the Matgéné program). The matrices produced are specific to a given hazard and provide semi-quantitative indices of probability and level of exposure for all exposed occupations and industries, coded according to French and international classifications. These matrices have numerous potential applications. In particular, they will make it possible to estimate the prevalence of occupational exposures in the population and to study variations in this prevalence by sex, age, region, occupation, sector of activity, and time period. Several matrices (flour dust, cereal dust, leather dust, cement dust; mineral wool; petroleum solvents broken down into subfamilies) have been completed or are currently undergoing validation. By way of illustration, the matrix concerning flour dust is presented in greater detail, with examples of its application. Other matrices are currently being developed: free crystalline silica dust, refractory ceramic fibers, oxygenated solvents, and chlorinated solvents. For each matrix, a fact sheet is produced, defining the technical characteristics of the matrix, describing the sectors where the hazard is encountered, and providing information on the prevalence of exposure. (R.A.)