In the home, heating and cooking equipment are possible sources of carbon monoxide. Vehicles running in an attached garage could also produce dangerous levels of carbon monoxide. However, consumers can protect themselves against CO poisoning by maintaining, using, and venting heating and cooking equipment and by being cautious when using vehicles in attached garages. CO replaces oxygen in the bloodstream, eventually causing suffocation. Mild CO poisoning feels like the flu, but more serious poisoning leads to difficulty breathing and even death.
Higher concentrations are dangerous even for a short time.
Carboxyhemoglobin levels do not consider the length of exposure. As more and more carbon monoxide accumulates in the blood, the percentage of COHb gets higher and higher and people get sicker and sicker. Three of every five of these deaths typically involve vehicles, one of every five typically involves heating or cooking equipment, and the other one of every five typically involves other or unspecified causes. In fact, deaths from unintentional carbon monoxide poisoning have dropped sharply in recent years, thanks to lower CO emissions from automobiles and safer heating and cooking appliances. Published estimates on the role of CO in home fire deaths vary widely.