Since occupational asthma (OA) is one of the most widespread occupational lung diseases, the CSST introduced a detection and compensation program making it possible to remove victims from their workplace as soon as the diagnosis is made. Despite this proactive approach, 70% of afflicted workers continue to show OA symptoms after being removed from exposure to the causal agent. A recent study showed that the health of those with bronchial eosinophilia at the time of their exposure to the occupational agent concerned took a turn for the better following their removal, which was not the case of the others. The purpose of this activity is to assess whether the absence of eosinophilia during exposure to the allergen responsible for OA at the time of the diagnosis makes it possible to identify a group of workers whose long-term prognosis is poorer, even after their removal from exposure. If the health of the subjects without eosinophilia proves to evolve less favourably than that of those with the condition, it would be necessary to prescribe longer follow-up in their cases and perhaps the testing of other therapeutics than those currently being offered them.