Abstract: At approximately 4:00 a.m. on November 2, 1995, Employees #1 through #5 were working the third shift in the collagen products department for a manufacturer of leather and collagen products. They reported symptoms associated with carbon monoxide poisoning, including severe headaches, nausea, and vomiting. The facility nurse checked on the employees and had them admitted to the hospital for observation. The first and second shift employees were also sent to the hospital for observation. One second shift employee was admitted. Employees #1 through #13 were treated, and those who were admitted stayed in the hospital approximately six to eight hours before being released. Carboxyhemoglobin tests indicated that the employees had elevated levels of carbon monoxide, some significantly elevated. An inadequately tuned Toyota forklift truck was being run in the approximately 25 ft by 100 ft by 18 ft high work area, moving large containers of hides from one area of the building to another. In addition, the collagen department is in an old building with no heat. A Universal propane heater was being used while the two large overhead doors were closed, and the building had no mechanical ventilation. All employees recovered from their exposure.