A fire broke out on a mixer in a plant dedicated to the compaction and storage of chlorinated tablets for swimming pool maintenance. The equipment with a capacity of 1,200 l contained 450 kg of raw materials comprising 55% of trichloroisocyanuric (ATCC) and 43% of sodium carbonate. The establishment’s internal emergency plan was activated and the plant’s staff was evacuated. The site was secured, while 3 employees equipped with respiratory masks removed anything from the area that could help to spread the fire. The alert was lifted 3 hours later after the raw material contained in the mixer had completely decomposed. No one was injured and material damage was limited to the mixer which was out of commission. The production line involved was shut down for 2 weeks, and the entire plant’s production was only stopped for 8 hours to clean the installations. Regarding the environmental impacts, a cloud of toxic fumes was blown over the site. According to the operator, 200 kg of ATCC had burned, with the combustion having been initiated when the mixer was being emptied into the compactor at 50% of its capacity. After analysis, it would seem that the fire started on the bearing between the reducing gear and mixer shaft. Mechanical friction, perhaps combined with a organic matter (grease) from the reducing gear bearing, could have been the cause of the accident. To reduce the likelihood of the recurrence of such an event, the operator is considering the installation of a new mixer that overcomes the shaft friction problem. An emergency prefectural order, issued on 30/03/04, instructed the operator to analyse the risks specific to production units and study the impact, in terms of risk, of the variation in formulation of the raw materials, especially including the resistance to heating and behaviour in relation to organic matter.