Abstract: At 1:15 a.m. on March 6, 1991, a power failure occurred at a security monitoring company, causing a back-up gasoline-powered generator to engage in the basement. At 2:00 a.m., Employee #1 began to experience symptoms of carbon monoxide poisoning. He was transported to a hospital's emergency room and treated. The generator had been improperly installed, according to the owner's manual instructions that warned against using the generator in enclosed areas. The exhaust pipe installation did not meet NFPA standards, which required a flexible connector. It was also installed with an electrical conduit pipe joined with compression fitting. The pipe connection vibrated loose, allowing fumes to emit through gaps in the floor between the employee's work area and the basement. The exposure was calculated to be 550 ppm over a 15 minute average and 78.1 ppm 8 hour TIWA.