Abstract: On November 10, 1992, Employees #1 and #2 were exposed to blast furnace gas that contained 22 percent carbon monoxide when there was a malfunction of equipment that opens and closes valves from which gas flows into a stove at a steel mill. Employee #1, a stove tender who was at the #4 stove when the valve failed to close, was asphyxiated and killed. His blood was found to have a carboxyhemoglobin level of 65.9 percent. Employee #2, employed by an outside contractor, was operating a bulldozer at a slag pit and was approximately 50 yards from the stove. Although he was exposed to lower levels of carbon monoxide, he developed an acute myocardial infarction and died.