Carbon monoxide (CO) is a colorless, odorless, and tasteless gas. This invisible, poisonous gas is produced from burning fuels such as natural gas, gasoline, fuel oil, or wood (for example, in indoor heating systems, car engines, cooking appliances, or fires).

If fuel-burning appliances are installed and used properly, very little carbon monoxide is produced. If the appliances are not maintained or used properly, dangerous levels of carbon monoxide can build up in enclosed areas, such as in houses and buildings. The exhaust from cars can reach dangerous levels in an enclosed area such as a garage—even when the garage door is open—and can leak back into the house. Fatal concentrations can also build up in semi-enclosed or even open areas, including swim areas behind house boats.

When a person inhales carbon monoxide, it begins to replace the oxygen that is carried in the blood. This is because carbon monoxide binds to red blood cells 230 times more strongly than oxygen does. The condition that results is called carbon monoxide poisoning . As the oxygen in the blood is replaced by carbon monoxide, the body's organs and tissues, which depend on oxygen, cannot function properly. A person who has carbon monoxide poisoning may develop headaches, dizziness, or nausea. If the exposure continues, the person may lose consciousness and even die.

The current, most effective treatment for carbon monoxide poisoning is oxygen therapy . Oxygen therapy replaces the carbon monoxide in the blood with oxygen.

Carbon monoxide poisoning can be hard to identify. The symptoms of headache, dizziness, and nausea can also be caused by several other illnesses. If you think that you have been exposed to carbon monoxide, your health professional can test you for carbon monoxide poisoning.