How does carbon monoxide get into your home?

Carbon monoxide (CO) is a common by-product of the combustion (burning) of fossil fuels. Most fuel-burning equipment, such as the furnace in your home, if installed properly and maintained regularly, produces little CO and are vented to the outside. However, if anything disrupts the venting process (something clogging the chimney or vent pipe) and results in a shortage of oxygen to the burner, the presence of carbon monoxide can quickly rise to dangerous levels. Additionally, the burning of wood, coal, kerosene and charcoal produce CO, as well as gasoline engines. Starting your gas lawnmower or idling your car in the garage can be dangerous not only in the immediate area, but CO can enter your home through connecting walls and doorways.