This article highlights that some heat-related deaths can be prevented. The key is to identify vulnerable populations and understand the risk factors. Excess mortality primarily affected older adults living at home or in care facilities. After presenting the research on risk factors, the article discusses a study conducted as part of the Air and Health Surveillance Program led by the InVS in nine French cities. The study aims to estimate the excess mortality risk associated with exposure to temperature and air pollution and to determine the proportion attributable to each of these factors, as well as their mutual potentiation.