In a company manufacturing printed circuits, a tank containing hydrochloric acid overflowed onto a retention tank. The acid was mixed with around 100 litres of sodium hypochlorite or sodium chlorite already present in the tank. A could of chlorine gas was formed and spread to the entire building. Five employees were intoxicated and hospitalised. One of them was under observation for over 48 hours. The fire-fighters neutralised the chemical and aerated the premises. The accident may have resulted from the failure of a solenoid valve. This accident would not have occurred if the tanks containing two incompatible chemicals did not have a common retention tank.