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 house, appliances that need natural gas, charcoal, wood or kerosene are susceptible. Especially if they are not working properly or have been installed wrong.
Vehicle exhaust fumes from nearby garages, as well as malfunctioning fireplaces may also create carbon monoxide. CO is toxic to the body and is lethal at increased levels or with long exposure.