Carbon monoxide (CO) is a clear, odorless and tasteless gas. It’s made by partial fuel combustion usually caused by not enough oxygen. In your house, appliances that consume natural gas, charcoal, wood or kerosene are susceptible. Especially if they are not running correctly or have been installed wrong.
Vehicle exhaust fumes from attached garages, as well as malfunctioning fireplaces may also be a carbon monoxide source. CO is poisonous to the body and is fatal at increased levels or with prolonged exposure.