In their day-to-day work, the five institutes face uncertainties regarding the quantification of health risks and the challenge of engaging with the public. The working group (WG) established for this purpose has developed a questionnaire covering the three phases of the health impact assessment process: the planning phase, the study implementation phase, and the phase involving the reporting and interpretation of results. This framework specifically addresses investigative processes for situations identified at the local level as potentially harmful. The legitimacy of the intervening institution, meeting public expectations, transparency regarding what can and cannot be done, developing partnerships with the public, and formulating and following up on recommendations are all key points that emerged from the WG’s work. These points were reinforced during hearings with local elected officials and associations. Throughout the processes undertaken with the public, the time invested plays a significant role in the success or failure of managing the situation. (R.A.)