Abstract: On July 17, 2003, Employees #1, #2, #3, and #4 were exposed to a hazardous gas. The employees were sanitizing a conveyor belt at a hog killing meat packer. Sanitizing the conveyor belts is done over six nights. For four nights chlorine based cleaners are used and on two nights an acid based cleaner is used. After the belt was cleaned with rags soaked in the chlorine solution, the gray bucket containing the rags was placed next to a red bucket containing acid cleaners. A rag was hanging between the two buckets. An employee took the gray bucket and rags and dumped them on a boot wash grating to dilute the possible chemical reaction between the two cleaning solutions. When the 140 degree water from the hose was applied to the rags the hazardous gas was emitted. The employees were assisting in the evacuation and sustained chemical burns and were hospitalized. The exact reason for the release was unclear. It could have been the result of residual acid cleaners on the concrete under the grating, the 140 degree water increasing the contact between the two cleaners, or someone dumping an acid cleaner in the grating/drain during the hosing off of the rags.