Abstract: On or about April 14, 2009, Employee #1, a truck driver, pulled his tanker truck containing a load of naphthenic waste caustic from Citgo refinery in Lake Charles, LA, adjacent to a processing tank NV-1, and connected it to discharge his load to the process tank. He was observed opening the dome lid to the tanker. Evidence suggests he may have been exposed to hydrogen sulfide while opening the dome lid, became light-headed, and may have fallen either on the top of the tanker, or as he attempted to descend the ladder from the tanker. He apparently then sat in a chair about 50 feet from the process vessel, and then toppled from the chair, unresponsive. There was conflicting information regarding whether he was administered oxygen. A coworker called 911, and another performed CPR. Employee #1 was declared dead on arrival at the hospital.