In a town in the Val d'Oise department, residents living near a former industrial site have been exposed for several years to benzene and other light hydrocarbons present in the indoor air of their homes. The Regional Health Agency (ARS) requested assistance from the Regional Unit of the French Institute for Public Health Surveillance (InVS) (Cire) for the Ile-de-France-Champagne-Ardenne region to assess the exposures and associated health risks, and to provide decision-making support to determine whether individual or collective health management measures should be implemented for the residents. Benzene was selected as the risk marker. At the concentrations detected in living spaces, the effects of chronic exposure would be an increased risk of malignant hematological diseases. The excess risk of cancer possibly linked to benzene remains low compared to the number of malignant hematological diseases normally expected in the general population. However, the risk levels are clearly unacceptable under the national policy on contaminated sites and therefore justify a rapid reduction in exposure. Monitoring exposure through the measurement of benzene biomarkers would face difficulties in interpretation and the lack of laboratories capable of measuring these markers at environmental levels. While the implementation of organized screening for early effects of benzene (via complete blood count) was not deemed appropriate, providing information to physicians practicing in the area and offering toxicological consultations for exposed individuals were proposed to the ARS.