Dear Doctor: I have heard several stories on the news recently about carbon monoxide-related deaths, and they have me concerned. Where does carbon monoxide come from, and how do I protect my family?

Dear Reader: Carbon monoxide, also referred to as CO, is a colorless and odorless gas that is impossible to detect without specialized equipment. Because of that, it has been called the “invisible killer.” About 400 people die each year from CO poisoning, and another 20,000 seek medical treatment.

In the home, carbon monoxide can be produced by fuel-powered devices like stoves, furnaces, water heaters, dryers, boilers and lanterns. It is emitted by wood-burning fireplaces, charcoal grills and generators. Virtually any substance that contains carbon and can burn will produce carbon monoxide as a byproduct.

The reason carbon monoxide is so toxic is that, when we breathe it in, it takes the place of oxygen in our red blood cells. In fact, the chemical structure of CO is such that it binds far more readily to the hemoglobin in our blood than does oxygen.

When you’re breathing in an enclosed space where CO is present, your body will become starved for oxygen in a very short time. Cells and tissues that are denied oxygen quickly begin to die. Brain cells, for example, begin to die after just three minutes without oxygen. Beyond that, permanent brain damage begins.

Now, some good news. The presence of carbon monoxide in the home is easily detected by special alarms. Just like a smoke alarm, the CO alarm contains specialized sensors that will activate when the gas approaches unsafe levels. These alarms, which can plug into electric outlets and also have backup batteries, are sensitive, accurate and affordable. In many states, they are required by law.

It is recommended that a CO alarm with a backup battery be installed on every level of the family residence, including the basement, attic and garage. There should also be a CO alarm outside of each sleeping area.

There are several other steps that you can take to keep your family safe.

— Perform a monthly test of each CO alarm to be sure it is working.
— Keep a supply of extra batteries on hand, so they can be replaced right away.
— When you use your fireplace, be sure the damper is wide open. Leave it open until the ashes have completely cooled.
— Never use your gas stove or oven to heat a room in your home.
— Never use a portable generator in the house or in any enclosed space. Generators should be kept at least 20 feet from the home when in use.
— Don’t use a gas or charcoal grill inside the home. Be sure to operate grills far away from any open windows.
— Know the symptoms of carbon monoxide poisoning: weakness, dizziness, sleepiness, headache, weak pulse, nausea, vomiting and confusion.

If you suspect that you or a family member has CO poisoning, immediately go outside to the fresh air, and then call 911.

Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health.