On September 26, 2019, a major fire broke out at the Lubrizol and NL Logistique warehouses located in the Rouen port area. The fire produced a large plume of smoke that drifted northeast, accompanied by soot fallout and very unpleasant odors. Many workers present at their workplaces near the fire or under the smoke plume may have been exposed to emissions from the fire or its consequences (stress, soot deposits, odors, etc.). In addition, several dozen companies were also on-site at the fire location on the same day and until the end of the cleanup operation. In response to a referral from the Ministry of Health, an epidemiological assessment of the health consequences of this fire was established by Santé publique France, “Santé post-incendie-76,” with a component addressing worker health. In response to a proposal from the Normandy Occupational Health Alert Group (GAST), this document outlines the protocol adopted to establish epidemiological surveillance of workers’ health using the National Health Data System (SNDS). The objective is to monitor and describe, in a manner similar to that used for the general population, the health status of workers exposed to the fire or its aftermath and to compare it with that of reference workers in order to identify potential increases in the occurrence of health events. The study area is similar to that of the general population study "A Study Listening to Your Health" and includes 119 municipalities in Seine-Maritime. The population of workers involved in the follow-up is divided into three categories: • workers who responded at the fire sites; • employees of companies (public or private) located near the fire; • employees of companies (public or private) located across all 119 municipalities. These workers will be identified either directly through their employers or via pension fund databases. The health indicators being monitored generally pertain to healthcare utilization and hospitalizations for various conditions, which may be assessed in the short term (3 weeks after the fire) or long term (more than 5 years after the fire), depending on the type of condition. In addition to a presentation of the selected methods, the protocol outlines the various stakeholders and their roles, the nature and flow of data, the measures taken to ensure data security, and the procedures for individuals to exercise their rights.