Pollution
Humain
Environnement
Economique

The opening of a safety valve at nitric acid plant caused release of a about 500 kg of nitrous gases into the atmosphere in about 2.5 minutes. The emission of nitrous gases did not endanger the environment as it was subsequently confirmed by the measurement values (0,5 à 5 ppm). Dutch defence program did not alarm Dutch population whereas Belgium’s authorities activated a civil defence and broadcast alarm messages.

The accident occurred due to dysfunction of a safety valve: it triggered too soon due to defective auxiliary control.