A chemical plant released hydrogen sulphide (H2S) into the atmosphere for 3 hours. Foul smells were noted east of the establishment up to 10 km away, leading many residents in the neighbouring cities to contact the fire department. This pollution was caused by a malfunctioning soda distribution pump on the gaseous effluent scrubbing installation of the strontium sulphide-manufacturing unit (SrS). On the day of the accident, batch production was underway for the first time in several years at the site as the older installations (reactors) had been coupled to a temporary system designed to convey gaseous effluents to the gas scrubbing installations. When production was launched, as the soda-scrubbing pump disconnected twice, the operator stopped the fabrication process without neutralising the chemical reaction. The process thus continued until the reagent (ammonium sulphide) was totally consumed, and resulting in the release of hydrogen sulphide. The Classified Installations Inspectorate acknowledged the facts and proposed that the Prefect require that all resumption of the installation’s activity be subject to a risk analysis. The operator considered doubling the pumps on the gaseous effluent treatment installations and re-evaluation of the site’s dimensioning