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