Carbon monoxide
Let’s get one of the most dangerous air pollutants out of the way, first: carbon monoxide. CO is an odorless, colorless gas that comes from burning fuel. Gas stoves, propane heaters and even your car running in an enclosed garage can cause a build-up of this noxious gas.
According to the Center for Disease Control and Prevention, 400 people in the US die from unintentional CO poisoning each year and more than 20,000 visits to the emergency room are caused by carbon monoxide.