Carbon monoxide (CO) is a colorless, odorless and tasteless gas. It is quite toxic to humans and other oxygen-breathing organisms. Carbon monoxide poisoning happens when enough carbon monoxide is inhaled. (See carbon monoxide poisoning)
Low levels of carbon monoxide are always present in air. It can also be produced from incomplete combustion of flame fueled devices such as fireplaces, furnaces, stoves, vehicles, space heaters and others.
Breathing carbon monoxide fumes decreases the blood’s ability to carry oxygen. Low levels of oxygen can lead to cell death, including cells in vital organs such as the brain and heart.