Carbon monoxide (CO) is a colorless, odorless gas given off by fuel-burning appliances such as gas heaters and gasoline-burning engines. CO can become deadly when these types of appliances are used indoors or without adequate ventilation. According to the CDC, about 500 Americans die every year from CO poisoning not related to a house fire, and more than 15,000 are injured.

Deaths and injuries peak in midwinter, when heater use is highest and when houses are tightly closed. Symptoms of CO poisoning include headache, dizziness, weakness, nausea, and confusion, and, because they resemble symptoms of other illnesses, people often do not realize they are being poisoned by carbon monoxide until it is too late.

In order to protect yourself against CO poisoning, you should have your gas heating system inspected every season. Don’t use generators or gasoline-powered heaters or tools inside, or in an enclosed space like a garage. Also, keep these CO-producers away from windows and intake vents, which can spread CO throughout the house.

Because CO is hard to detect, the best way to protect yourself from CO exposure is to buy a CO detector. They look like smoke detectors, and will sound an alarm if CO levels get too high. Be sure to play it safe and protect yourself against this deadly gas.