UNITED STATES
DEPARTMENT OF LABOR

A furnace operator noted lights indicating high carbon monoxide (CO) levels at most or all of the CO sensor locations. Shortly before 12:15 p.m., he notified Employee #1, the supervisor, that he thought the carbide bin might be empty. Employee #1 made a phone call about a different matter and then apparently went to fine feed level 2, where he was found dead at approximately 4:00 p.m. at the end of the shift. On level 2 there was an opening to the chute of the carbide bin and a rod could be inserted into this opening to unjam the chute. During subsequent investigation under non-alarm CO conditions, CO levels of over 1,000 ppm were measured at this opening. Employee #1's carboxyhemoglobin level was 56, which indicates exposure to CO levels over 1,000 ppm for 10 minutes or more. There had been problems with the indicator lights related to material levels in the carbide bin and some repair work had been done, but the problems continued. When the carbide bin and chute were empty, CO could flow up out of the furnace and create the type of alarm pattern noted by the furnace operator.