3 US Marines died of carbon monoxide poisoning in a car. Vehicle experts explain how that can happen

RALEIGH, N.C. (AP) — The seemingly accidental deaths of three U.S. Marines who suffered carbon monoxide poisoning in a parked car at a North Carolina gas station have raised questions about how the situation could have occurred outdoors. 

Deputies from the Pender County Sheriff’s Office had found the men unresponsive in a privately owned Lexus sedan in the coastal community of Hampstead. Autopsies performed last week by the North Carolina medical examiner’s office determined that all three died of carbon monoxide poisoning. Sgt. Chester Ward from the sheriff's office said the ongoing investigation indicates it was accidental. 

While the Centers for Disease Control and Prevention report that many U.S. carbon monoxide deaths occur inside homes or closed garages, automotive experts say certain vehicle malfunctions can cause casualties outdoors.  

Usually, those malfunctions are loud or smelly. If a car's exhaust system is broken or is leaking into the cabin, passengers would typically hear the engine making noises, said Jake Fisher, senior director of auto testing at Consumer Reports. Corrosion on an older car, such as the one involved in the Marines' deaths, can cause the hood to fill up with exhaust gases, which Fisher said can then get sucked into the cabin through an intake cavity between the hood and the windshield.