Abstract: Employees #1 and #2 worked at the wastewater treatment facility of a textile finishing plant. They were helping a tanker truck driver unload a shipment of sodium hypochlorite that had been misidentified as ferric chloride by plant security personnel. The security person relayed the mistaken product identity to the wastewater plan manager who passed on the information verbally Employees #1 and #2. They told the truck driver to connect the truck delivery hose to the ferric chloride tank and to begin pumping. As the sodium hypochlorite entered the storage tank, the chemical reaction of the mixture began to release chlorine gas into the atmosphere. Employees #1 and #2 were nearly overcome, but they managed to run away from the vapors.