According to the Centers for Disease Control, 50,000 people a year visit the emergency department because of carbon monoxide poisoning. Carbon monoxide is odorless and colorless, but poisoning can be prevented.
Resources to learn more include:
Carbon Monoxide (CO) Poisoning Prevention (CDC): http://bit.ly/2ab3kql
Carbon Monoxide Poisoning (MedlinePlus): http://bit.ly/29QhRWa