The sudden shutdown of a halogenated organic product incinerator in a chemical plant lead to the formation of an aerosol cloud that did not disperse at altitude. This malfunction caused the degassing flows to the scrubber to be saturated in organic amines. The scrubber receives acid and halogenated gaseous effluents to be processed. The neutralisation operation normally performed prior to the release to the atmosphere did not take place. The emission point at the scrubber outlet is located 8.7 m above the ground. The gaseous emissions lasted 43 minutes, from 5.23 am to 6.06 am, and formed an organic amine halide aerosol cloud (mist) estimated at less than 5 kg. The accident had no human consequences or property damage. The cause of the accident was attributed to a faulty maximum level sensor on the separator of the degassing circuit before entering the incinerator, leading to the undetected presence of organic liquids. The malfunction was caused by the lack of periodic verification to sure that the separator’s max. level measurement was operating correctly, even though it is subject to fouling caused by the presence of organic amine halides. The incinerator is shutdown several dozen times a year