The study of the links between the environment and health is a field marked by great complexity and uncertainty. However, at a time when health and the environment are the focus of significant public attention, these difficulties should not prevent us from addressing the health risks posed by the changes humans are inflicting on the environment. These risks, particularly those resulting from involuntary exposure to environmental pollutants, are becoming less and less socially acceptable, and the precautionary principle serves as a reminder that scientific uncertainties do not justify inaction. In this spirit, the impact assessments established by the 1976 law have recently been strengthened with regard to health risk analysis (Article 19 of Law No. 96-1236 of December 30, 1996, on air quality and the rational use of energy). This guide, developed at the request of the Ministry of Health, was designed to provide professionals in government agencies responsible for reviewing impact assessment reports prepared by applicants with the necessary information to conduct a critical review of the health section. It is therefore not a methodological guide for preparing this section. Rather, it aims to formalize what, from a public health perspective, should constitute its optimal content. Readers will thus find questions that enable them to establish the link between the impact study and the health section, as well as an evaluation grid to analyze and assess the studies presented to them. Consequently, petitioners will also find the criteria used by the administration to assess the quality of the submitted applications. The methodological framework selected is that of the health risk assessment (HRA) approach because it is both the most appropriate method for studying “future” risks and the most sophisticated for characterizing “low” risks. The HRA makes it possible to bridge the gap between environmental science and public health imperatives and helps ensure that decisions—which should no longer be rejected in the name of scientific uncertainty—are transparent, and thus enforceable and subject to improvement.