Industries sometimes leaves invisible yet dangerous chemical memories of their activities. Because these compounds are invisible, people rely on heuristics informed in part by people-place relations to make a risk judgement. The Marseille region of France provides an interesting case to analyse how local risks are judged in relation to people-place variables. The perceived risks of a depollution project where “red mud” (an industrial residue) is used to neutralize lead-contaminated soil are analysed in relation to (1) place attachment; and (2) trust in several types of organisation. Results show that participants with stronger local attachment perceive their local environment as less polluted and consider the project as a greater threat. Furthermore, risks vs. benefits associated with the project are significantly explained by age (associated with perceived risk) and trust in societal organisations (associated with perceived benefits). Discussion considers how the diversity of local publics could lead to widely different reactions to the depollution project across the city’s social tissue.