“Fire personnel located the room with the greatest concentration of the gas at 150 ppm. They discovered a detached exhaust pipe from a natural gas-fired hot water heater and determined the carbon monoxide…was being released in the room…If CO alarms were not present or not operating properly this incident could have surely proven fatal.

SHAES (South Haven Area Emergency Services) withheld the name and address of the hotel to preserve anonymity.”

South Haven emergency team evacuates hotel due to carbon monoxide (msn.com)