Carbon Monoxide Poisoning: Start Safe to prevent the ‘Invisible Killer’

According to the United States Centers for Disease Control, on average each year more than 400 Americans die, more than 100,000 visit emergency departments, and more than 14,000 are hospitalized because of carbon monoxide (CO) poisoning. Globally, these figures are much higher, with a 2023 study published byThe Lancet citing nearly 30,000 global CO poisoning deaths in 2021.

November is CO Awareness Month—an annual campaign spearheaded by the National Carbon Monoxide Awareness Association (NCOAA). This year, the theme focuses on “a lifetime of protection,”  from preparing for a new baby to protecting older adults.

What Is Carbon Monoxide?

CO is an invisible, colorless, odorless gas created when fuels—such as gasoline, wood, coal, natural gas, propane, oil, and methane—burn incompletely. Exposure to low levels of CO over a longer period of time or high levels of CO over a shorter period of time can result in illness or death.

CO is often referred to as the “invisible killer” because people are often unaware of their exposure, and the effects of exposure, such as dizziness, sleepiness, and headaches, mimic other health conditions. Additionally, the dangers of CO exposure depend on a number of variables, including an individual’s health, activity level at the time of exposure, duration of exposure, body size, and rate of oxygen metabolization, according to a study published in January 2026 by the Fire Protection Research Foundation.

Safe Heating and Energy Practices

The leading source of non-fire CO deaths in homes in the U.S. is portable generators, followed by heating appliances and systems. Because of this fact, generators and heating appliances require careful use to help keep people safe. Following these important safety tips can help you avoid CO exposure:

• Use generators outdoors in well-ventilated areas at least 20 feet (7 meters) from all doors, windows, and vent openings.

• Never use a generator in an attached garage, even with the door open.

• Place generators so that exhaust fumes can’t enter the home through windows, doors, or other openings in the building. The exhaust must be directed away from the building.

• Have fuel-burning heating equipment and chimneys professionally inspected before use each year.

• Never use a stove or oven to heat your home.

These tips and others can be found in our Generator Safety tip sheet, as well as our Carbon Monoxide Safety tip sheet.

The Importance of Carbon Monoxide Alarms

One of the most important ways to safeguard against exposure to CO is to install CO alarms. Easy to find and use, CO alarms help keep every member of the family safe. A few tips to keep in mind about CO alarms include:

• Choose a CO alarm that is listed by a nationally recognized testing laboratory.

• Follow the manufacturer’s instructions for placement and mounting height.

• Install CO alarms in a central location outside each sleeping area and on every level of the home and in other locations where required by applicable laws, codes, or standards.

• Test alarms at least once a month; replace them according to the manufacturer’s instructions.

• Move immediately to a fresh air location outdoors or by an open window or door when the CO alarm sounds. Make sure everyone inside the home is accounted for. Call for help from a fresh-air location and stay there until emergency personnel arrives.

Safety During Cold Weather

Although CO safety is important to keep in mind year-round, data shows that more CO poisoning deaths occur during winter months than any other time of year.

There are a few safety tips specific to staying safer during cold or snowy weather, such as:  

• If starting a car and leaving it running to warm it up, remove it from a garage first. Do not run the vehicle inside a garage, even if garage doors are open.

• Before starting a car in snowy weather, make sure the exhaust pipe of the vehicle is not covered with snow.

• Clear snow buildup from vents for the dryer, furnace, stove, and fireplace both during and after a snowstorm.

• Open the flue for adequate ventilation when using a fireplace.

Learn More

Together we can help protect families from the dangers of carbon monoxide. For more information and resources about CO safety, including videos and free, downloadable tip sheets, visit our Carbon Monoxide Safety webpage.

And learn more about NCOAA and CO Awareness Month in November by visiting ncoaa.us.