Carbon monoxide is a common byproduct of the combustion (burning) of fossil fuels. Most fuel-burning equipment (natural gas, propane, and oil), if properly installed and maintained, produces little CO. The byproducts of combustion are usually safely vented to the outside. However, if anything disrupts the venting process (such as a bird's nest in the chimney) or results In a shortage of oxygen to the burner, CO production can quickly rise to dangerous levels.
Carbon Monoxide Production
The burning of wood, kerosene, coal, and charcoal and gasoline engines produce CO. CO production is at a maximum during the startup of a cold engine. Starting, then idling, your car or gas mower in the garage can be dangerous. The fumes that contain CO can enter a home through connecting walls or doorway and can quickly rise to dangerous levels.