Fire broke out around 5:45 am at a site specialised in the production of sulphur flakes from hot liquid sulphur. On the day of the accident, 872 tonnes of solid sulphur were being stored, including 250 tonnes in hangar “A” (where the fire started). A large gaseous sulphur dioxide cloud was released; 3 individuals were intoxicated. This sulphur cloud hindered visibility on the A16 motorway, causing an accident involving 9 cars, 2 trucks and a motorcycle that injured 5, one of whom seriously. Traffic on the A16 was closed in both directions and 2 helicopters were commissioned for surveying. The Prefecture ordered 80,000 residents from 4 municipalities to remain indoors. The Belgian Interior Ministry’s crisis unit was informed. The blaze was extinguished around 9:40 am following the intervention of fire-fighters wearing breathing masks and deployment of 4 fire hoses (1 mounted on a ladder). At 10:30 am, air quality controls no longer revealed any significant quantities of sulphur; the residential confinement order was lifted at 10:45 am.

Since the company was not equipped with any retention facilities, the extinction water (approx. 60 m³) flowed into the BOURBOURG canal via a sump and a pipeline, as well as into the ground through an infiltration pipe dedicated to the stormwater system. The appropriate water agencies were notified. According to the site operator, 4 tonnes of sulphur were consumed in the fire. The hangar had not been equipped with either a sulphur dioxide detector or smoke vents.

The operator provided employees with SO2 detectors and, while awaiting installation of a video surveillance system, hired a subcontractor to monitor the site during unoccupied periods. At the suggestion of the Classified Facilities Inspectorate, the Prefect issued an order to: install SO2 detectors in the storage hangars, clean out all sewer lines potentially containing sulphur, and extract sediment samples from the canal. Two months to the day, fire once again broke out in another sulphur production hangar, this time detected by the 28 sensors installed after the previous fire and quickly brought under control by fire-fighters alerted through the security company (ARIA 36205). The operator suspected arson as the cause of both fires and decided to strengthen security at the site, whose expanse (2 ha) had complicated surveillance efforts.