Certain areas in the Rhône-Alpes region are home to a concentration of industries, heavy road traffic, and large populations, raising questions about the health impacts of air emissions in these areas. Three areas were selected for the study, where the chemical industry is particularly well-established: southern Lyon (Pierre-Bénite, Saint-Fons), southern Grenoble (Pont-de-Claix, Jarrie), and the middle Rhône Valley (Roussillon, Salaise-sur-Sanne). With the aim of informing local stakeholders and assisting in the definition of priorities for action regarding emissions reduction, the objective of the study was to use metrology to: - assess chronic inhalation exposure to VOCs, PAHs, and heavy metals emitted by outdoor pollution sources in the neighborhoods most exposed to these sources within the study areas; - estimate the potential health risks associated with these exposures. The measurements were funded by the Rhône-Alpes Regional Directorate of Health and Social Affairs (DRASS). They were conducted by Atmo Rhône-Alpes in 2006/2007 with 2 or 3 measurement points per study area, 4 measurement campaigns (one per season), totaling approximately 36 days of sampling for each pollutant and each measurement point. Atmo Rhône-Alpes prepared an independent report detailing the metrological results. Eleven chlorinated VOCs, 5 ozone precursor VOCs, 2 aldehydes, 4 heavy metals, and 15 PAHs were selected for the health risk assessment. For many of these pollutants, the measured concentrations varied significantly from one day to the next, with occasional significant pollution peaks. Under these conditions, the days sampled could influence the calculated annual average exposure concentrations. Furthermore, it was assumed that the concentrations measured in 2006/2007 could be used to estimate average human exposures over long periods. This constituted the major uncertainty in the risk assessment. For many pollutants, the concentrations measured at different monitoring points within the same area were fairly similar, which allowed for a certain degree of homogeneity in exposures to be assumed in the neighborhoods surrounding the monitoring points. However, specific situations were identified for certain pollutants near certain monitoring points. Despite these limitations, the study demonstrated the value of using measurements to assess health risks from inhalation associated with emissions of VOCs, PAHs, and heavy metals. The risk assessment indicated that no systemic effects were expected in the study areas related to the exposures examined, but that inhalation exposures to certain VOCs were likely to pose carcinogenic risks. These included: - for the southern Lyon area: vinyl chloride monomer (particularly in Saint-Fons), benzene, 1,3-butadiene, tetrachloroethylene (in Pierre-Bénite and Saint-Fons), acetaldehyde (in Saint-Fons); - for the southern Grenoble area: formaldehyde (in Jarrie), benzene, 1,2-dichloroethane (in Jarrie); - for the Roussillon area: benzene. From a public health perspective, these VOCs were therefore identified as those requiring priority action to reduce emissions. However, inhalation exposure concentrations to certain VOCs in the study areas, combined with external pollution sources in these areas, were lower or of the same order of magnitude as indoor exposure concentrations within the homes of the entire French population (due to indoor pollution sources). Furthermore, the potential excess number of cancer cases in the study areas likely to occur in connection with the exposures studied (assuming similar exposure concentrations in the past and future) remained very low compared to the total expected number of cases. (R.A.)