Abstract: On December 18, 1994, Employees #1 through #3 were overcome by carbon monoxide poisoning while performing bulk mail "blending" operations at a temporary job site. The warehouse had been outfitted with two Reddy portable kerosene heaters (100,000 Btu), which had a warning label stating "Death or serious injury may result from carbon monoxide poisoning." The shift started at 3:00 p.m. At 5:00 p.m., Employee #1 was rendered unconscious and was transported by private vehicle to the hospital. Operations continued at the job site. The hospital staff alerted the fire emergency rescue unit, which arrived at the site by 5:50 p.m. Paramedics screened all the remaining employees, about 17 out of 24, for carbon monoxide poisoning. Employees #2 and #3 were determined to have the symptoms of carbon monoxide poisoning and were transported to the hospital by the fire rescue unit. At about 6:20 p.m., the remaining employees were released from work and sent home. The hospital used hyperbaric chambers to treat Employees #1 through #3. The chambers enhance oxygen absorption rates.