Abstract: At 6:45 a.m. on March 22, 2018, an employee and a coworker were standing on a work platform around a processing tank and preparing to add a potassium hydroxide/sodium hypochlorite solution from a 250-gallon tote into a 6,000-gallon processing tank containing an acidic copper sulfate solution. The employee opened the valve on the tote of potassium hydroxide/sodium hypochlorite solution and, when mixed with the copper sulfate solution, produced chlorine gas. The employee stayed on the platform to close the valve and stop the reaction. The employee moved to the back of the platform for fresh air but experienced a shortness of breath, chest burning and pain, coughing, and dizziness. The employee jumped off of the platform and was taken to the hospital where he was admitted for Chlorine gas poisoning.