DUE TO UNSEASONABLY COLD WEATHER, THE OPERATOR WAS USING A PROPANE HEATER TO WARM HIMSELF WHILELOADING RAIL CARS. HE STOOD TOO CLOSE FOR TOO LONG CAUSING IGNITION. HE COULD NOT REMOVE HIS OVE RALLS BEFOR BEING INJURED. HE RECEIVED MEDICAL ATTENTION & RETURNED TO WORK THE NEXT ASSIGNED SHIFT.