Abstract: At approximately 10:00 p.m. on April 27, 2010, Employee #1, a maintenance technician, transferred approximately 26 to 28 gallons of a rejected batch of a lactic acid and water mixture into a 55-gallon drum that originally contained liquid sodium hypochlorite. As a result, there was an apparent chemical reaction that generated a strong odor, possibly chlorine gas. Employees were evacuated from the building. A total of eight employees were transported via ambulance to two area hospitals. Four were transported to Elmhurst Hospital and four were transported to Loyola University Medical Center. The four individuals transported to Loyola University Medical Center were admitted for observation. The affected individuals experienced upper respiratory irritation, nausea, and irritation of the eyes.