Carbon monoxide (CO) is an invisible, odorless and tasteless gas. It’s made by insufficient fuel combustion often caused by insufficient oxygen. In your house, appliances that rely on natural gas, charcoal, wood or kerosene are susceptible. Especially if they are not running properly or have been installed wrong.
Vehicle exhaust fumes from attached garages, as well as fireplaces that aren’t working right may also create carbon monoxide. CO is poisonous to the body and is fatal at heightened levels or with long exposure.