Abstract: EMPLOYEE #1 LIVED IN A SMALL TRAILER, OWNED BY HIS EMPLOYER, AND LOCATED ON THE COMPANY'S PREMISES. THE EMPLOYEE WAS OFF DUTY, LYING ON THE COUCH IN THE TRAILER, WHEN HE WAS OVERCOME BY CARBON MONOXIDE, APPARENTLY GENERATED BY AN IMPROPERLY VENTED PROPANE HEATER. SEVERAL HOLES IN THE EXHAUST DUCT ALLOWED CARBON MONOXIDE TO ESCAPE INTO THE TRAILER. THE RETURN AIR INTAKE FOR THE COMBUSTION CHAMBER, LOCATED ADJACENT TO THE EXHAUST, PROBABLY PROVIDED TOO LOW A CONCENTRATION OF OXYGEN TO PERMIT COMPLETE COMBUSTION, THUS INCREASING THE CARBON MONOXIDE OUTPUT. AN AUTOPSY REVEALED THAT EMPLOYEE #1 HAD A CARBOXYHEMOGLOBIN BLOOD LEVEL OF 50%.