A clear odorless gas formed from the incomplete combustion of carbon-based fuels. Carbon monoxide is a short lived gas in the lower layer of the atmosphere. Sources of carbon monoxide include: cigarette smoke, blocked fireplaces and gas stoves, idling cars.

EPA – Carbon monoxide is an odorless, colorless and toxic gas. Because it is impossible to see, taste or smell the toxic fumes, CO can kill you before you are aware it is in your home. At lower levels of exposure, CO causes mild effects that are often mistaken for the flu. These symptoms include headaches, dizziness, disorientation, nausea and fatigue. The effects of CO exposure can vary greatly from person to person depending on age, overall health and the concentration and length of exposure.