Santé publique France was commissioned by the Provence-Alpes-Côte d'Azur Regional Health Agency (ARS) in March 2017 to analyze the methodology used in the "Fos-Epséal" study conducted in Fos-sur-Mer and Port-Saint-Louis-du-Rhône, as well as the resulting findings regarding the health effects of industrial exposure on the population. To respond to this request, Santé publique France formed a support committee composed of in-house scientists and experts from outside the Agency. The issues addressed by this committee were: a critical analysis of the study’s methodology and results; and the contribution of the participatory approach proposed by the study. The Fos-Epséal study is a participatory environmental health study (an approach known as “locally grounded epidemiology”). It was conducted by a team from the Norbert Elias Center in Marseille (EHESS, CNRS, University of Avignon, University of Aix-Marseille) in collaboration with an American team (College of Liberal Arts and Human Sciences, Virginia Tech University; School of Public Health, University of California, Berkeley) and funded by an ANSES call for research proposals. The committee concludes that the report would have benefited from a clear presentation of the methods used and a rigorous structure separating the statistical results from their interpretation. The comparison of statistical results based on respondents’ statements with regional or national reference data reveals excess risks for several conditions within the population sample of the surveyed municipalities. However, the committee considered that the existence of these excesses and their magnitude are limited by selection biases in the surveyed sample, the reference data selected, and the adjustment methods used. Despite methodological weaknesses, the results presented confirm that this area requires close attention from public authorities. The arguments used to link a health outcome (a locally observed excess of a condition) to an environmental cause, presented in the study as “elements of participatory analysis,” should be considered as hypotheses put forward by researchers and the public, which more precise ad hoc studies would be able to confirm. The focus on diseases of public concern, the consideration of health as expressed by the population, and the consultations conducted during the Fos-Epséal study represent the key strengths of this study. The locally grounded epidemiological approach, based on the perceptions and experiences of local communities, appears to complement the traditional epidemiological approach. The coexistence of these two approaches is useful for maintaining the credibility and optimizing the effectiveness of the French environmental health alert system.