Abstract: On August 14, 1991, Employees #1 through #23, of American Lockstitch Corp. were working on drapes and accessories in a plant. A propane-powered forklift truck was being used to load and unload boxes from delivery trucks and move materials inside the plant. The forklift driver had used his truck for approximately 5 hours; the motor was actually running for 2 hours. The air conditioning system recirculated air inside the plant rather than using air from outside, and two bay doors were the only source of ventilation. By the 2:00 p.m. break, most of the employees were experiencing headaches, and several had been nauseous. The plant manager was aware of the problem and evacuated the plant at 2:30 p.m. Twenty-nine employees were seen at Stanley Memorial Hospital. Four of these were admitted and four were taken by helicopter to Carolinas Medical Center for treatment in a hyperbaric chamber. Carboxyhemoglobin levels ranged from 0.0 percent to 21.7 percent. Back calculation of exposure levels were up to 356.2 ppm, as 8-hour time weighted average in air based on the Biological Exposure Index as found in the Documentation of Biological Exposure Indices, 1986.