Abstract: Employee #3 mixed a mineral oil/tall oil fatty acid compound with a sodium dichloro-s-triazinetrione dihydrate compound in a 5-gal PVC container to treat a water tower. The two chemicals reacted and began to burn the container. Employees #1 and #2 noted that the bucket was smoking. Employee #2 grabbed the bucket and ran 200 ft out of the parking garage to the edge of the property. Employees #1 and #3 followed Employee #2 out of the parking garage. Employee #2 then re-entered the garage to turn off the chillers, and Employee #3 re-entered to move his truck and obtain emergency phone numbers from it. Employee #1 inhaled PVC decomposition products and felt ill. Employees #1 and #2 went to Seton Hospital for medical evaluation, but were not hospitalized. Subsequently, 14 employees from the building went to the hospital; none were admitted.