Abstract: On November 18, 2009, Employee #1, of Machine & Welding Supply Company, was working on cylinder maintenance located adjacent to the medical cylinder fill plant. Employee #1 moved approximately eight to ten cylinders onto an exterior rear loading dock. Employee #1 was venting/bleeding down the contents so they could be repaired/scrapped. Employee #1 opened the valves on approximately three cylinders that did not have labels. One of those cylinders was determined to have contained arsine gas. Approximately two hours after exposure to the gas, Employee #1 began to experience symptoms such as, but not limited to, nausea, difficulty breathing, and numbness in his extremities. Employee #1 was hospitalized as a result of the exposure to the arsine gas. Employee #1 experienced a permanent decrease (50 percent) in renal function.