Carbon monoxide (CO) is a clear, odorless and tasteless gas. It’s created by incomplete fuel combustion frequently caused by insufficient oxygen. In your house, appliances that use natural gas, charcoal, wood or kerosene are susceptible. Especially if they are not running correctly or have been installed incorrectly.
Vehicle exhaust fumes from attached garages, as well as fireplaces that aren’t working right could also create carbon monoxide. CO is dangerous to the body and is fatal at high levels or with long exposure.