Abstract: Employees #1, #2, #3, and #5 were working in an area that was 30 ft by 50 ft by 20 ft high. Employee #4 was driving a propane forklift in and out of the area. In the afternoon, Employees #1 and #4 became sick and had to go to the hospital. Employees #2, #3, and #5 were called at home and told to report to the hospital to be checked for carbon monoxide poisoning. Employees #1 through #5 were found to have high levels of carbon monoxide and were referred to hypobaric therapy. The cause of the overexposure was apparently a combination of fumes from an unvented propane heater and fumes from the propane fork truck, which was in and out of an area in which doors had been closed due to cold. In addition, the edge bander equipment uses a glue (Rau-Bond hot metal adhesive) that decomposes into carbon monoxide.