Carbon monoxide (CO) is a clear, odorless and tasteless gas. It’s created by partial fuel combustion usually caused by not enough oxygen. In your residence, appliances that rely on natural gas, charcoal, wood or kerosene are vulnerable. Especially if they are not running properly or have been installed wrong.
Vehicle exhaust fumes from neighboring garages, as well as fireplaces that aren’t working right could also be a carbon monoxide source. CO is dangerous to the body and is lethal at increased levels or with prolonged exposure.