In a cleaning and toilet product manufacturing plant, a handling error occurred while a truck transporting a 50% liquid potash was being unloading, resulting in the substance being introduced into a tank of thioglycolic acid. An exothermic reaction between the two chemical substances resulted in the release of hydrogen sulphide. This mixture is generally implemented, in the presence of water, in the production of a hair removal product. In this case, the temperature of the reaction mixture without water is 60°C. The activation of an emergency stop button by an agent in acid/antigas gear and PBA stopped potash from entering the tank. As a precaution, the plant was evacuated, traffic stopped and the neighbouring school was informed of the situation. The truck driver was taken to the hospital. Measurements showed the presence of 130 ppm of H2S in the company’s basement level. A forced ventilation system was set up to eliminate the smell of H2S throughout the establishment. The operation took several hours. The potash unloading operation was then completed. Of the 37 production lines, 27 resumed operations the same day.