Carbon monoxide: an old poison with a new way of poisoning.

We present two events of carbon monoxide (CO) poisoning, which spread out through ventilation pipes to kill or injure neighbors. This is a previously undocumented poisoning process. In the first event, three people died and eight others suffered CO poisoning from a gas-powered water heater in an apartment building. Similar to the first event, three people expired and three others were injured by CO poisoning in the second event. We subsequently determined the cause of these tragedies were due to obstructions at the openings of ventilation pipes. CO is one of the most common causes of poisoning worldwide and these cases often result in tragedy. Early recognition of CO poisoning resulting from obstructed ventilation pipes will facilitate proper management and prevent possible lethal disasters. Additionally, all clinicians and other paramedical personnel ought to raise the suspicion of chemical-related casualties when encountering clusters of patients from a single locale.