On January 21, 2013, an industrial accident at a factory in the Rouen metropolitan area resulted in the release of a plume containing mercaptans, whose unpleasant odors prompted numerous complaints from local residents. To determine whether this event had an immediate health impact, the InVS Unit (Cire) in the Normandy region immediately strengthened the regional health surveillance system SurSaUD® by, on the one hand, consulting data from the regional surveillance and alert server (SRVA) and, secondly, by contacting emergency care services by phone whose operations might have been affected by the accident. The results indicate a very minor impact, involving mild symptoms, primarily headaches, dizziness, and irritations that were neither serious nor required medical treatment. Given the absence of any detectable impact, the surveillance system was lifted as of January 25. The lessons learned from this episode highlight the importance of having a responsive syndromic surveillance system, in addition to pollutant measurements and risk analyses, to assess the immediate health impact of an industrial accident. It also helps identify key areas for enhancing the effectiveness of such a health and epidemiological surveillance system in the event of an industrial accident: ensuring the network’s comprehensiveness and representativeness, proposing a specific coding approach in anticipation of an unusual event, and utilizing user-friendly, automated tools similar to those used for transmitting emergency department visit summaries (RPU). Furthermore, it has also become essential to expand and supplement the analysis of available data on industrial accident-type events in SurSaUD® with indicators specific to emergency medicine. (R.A.)