How to pick the right carbon monoxide detector to keep your family safe

Every year, more than 100,000 people are treated for carbon monoxide (CO) poisoning in the ER, more than 14,000 need to be hospitalized and at least 400 die from what is called a "silent killer." The winter months are when it's more likely people will experience CO poisoning, and this winter has seen multiple tragedies hit the headlines. These incredibly sad events re-emphasize the importance of having a CO detector and ensuring that it's working.

CO is a colorless, odorless gas that can leak from any appliance or part of your home that burns fuels such as gasoline, wood, coal, natural gas, propane, oil or methane.

Potential sources of CO include:

• Gas stoves

• Gas water and space heaters

• Wood stoves and fireplaces

• Gas or charcoal grills

• Gas dryers

• Kerosene heaters

• Fuel-fired generators

“Any fuel-fired appliances not properly installed, maintained or operated, including without adequate ventilation, can be a source of carbon monoxide,” says Laureen Burton, a chemist and toxicologist with the Indoor Environments Division of the Environmental Protection Agency (EPA). If appliances like those listed “are not functioning at their peak performance, there is a really high probability they will release carbon monoxide,” says Robin Zevotek, principal fire protection engineer for the National Fire Protection Association. That's because CO is released when fuel does not burn completely.

How to prevent carbon monoxide leaks

"CO poisonings can happen any time of the year but are often reported in winter months due to the increased indoor use of certain types of fuel-burning appliances and the closing up and/or tightening of buildings to protect from cold and/or other seasonal changes," says Burton. You can help prevent CO leaks by doing the following:

• Make sure any appliances that use fuel to produce heat are properly vented to the outdoors.

• Always make sure the flue is open before using your fireplace and keep it open until ashes are cool.

• Follow these EPA safety guidelines for any wood-burning elements in your home.

• Avoid using any unvented fuel-burning appliances (such as space heaters) inside.

• Hire a trained professional to regularly inspect, clean and tune up heating systems such as furnaces, flues and chimneys.

• Never use gas or charcoal grills indoors.

• Never run a vehicle or fuel-powered motor while it is inside your garage (even if the garage doors are open).

• Never use fuel-powered generators indoors. Instead, choose a well-ventilated outdoor location away from windows, doors and vent openings.

• During and after a snowstorm, make sure vehicle exhaust pipes and vents for dryers, furnaces, stoves and fireplaces are clear of snow accumulation.

How to choose carbon monoxide detectors

Aside from prevention, it's critical to have a CO detector installed in your home. In the event of CO buildup, these detectors function like a smoke alarm — they detect the gas at a level that could lead to poisoning and sound an alarm to alert you to its presence. While some states mandate and regulate CO detector usage, the regulations vary widely (and some states leave regulations up to local jurisdictions) so it's important to know what's legally required in your state (you can check your state here). In fact, according to a 2024 survey by the U.S. Consumer Product Safety Commission, approximately 42% of all homes don't have a CO alarm installed, and even in homes with alarms, approximately 16% are nonfunctional. This is why it's critical to know whether your detector is up to snuff, so to speak.

"You absolutely want to make sure that you have an alarm that is tested to UL2034," says Zevotek. That is an international safety standard written by UL Standards & Engagement, a safety advocacy organization that sets standards that products must follow to ensure they are using best practices to keep you safe. “Standard UL2034 requires alarms to report before CO reaches levels that cause a loss of ability to react,” says Melissa Dibble, a spokesperson for the Centers for Disease Control and Prevention (CDC). It also mandates that alarms meet a volume requirement to ensure people will hear them.

When purchasing a CO alarm, check the product packaging and labels for the words, “UL2034 Listed” or “UL2034 Certified,” and make sure it is well within the expiration period set by the manufacturer. Because the sensors lose their sensitivity over time, detectors must be replaced according to the manufacturer’s directions.

Beyond those two requirements, what type of alarm you pick depends on your preferences, but if you choose one that plugs in, you need to make sure it has a battery backup so it continues to work if the electricity goes out.

If you're looking for help narrowing down the choices, check out the suggestions at the end of this article.

Where to install CO detectors in your home

"Carbon monoxide alarms should be installed in a central location outside each sleeping area and on every level of the home," says Burton. "Sleeping rooms are the most important," says Zevotek, "because if they do detect CO, you want to be able to wake someone up." When you are sleeping, you may not experience the first warning symptoms of CO poisoning, such as headaches and weakness, and can progress to the most serious sign, loss of consciousness, without knowing.

"Since carbon monoxide is slightly lighter than air and will tend to rise towards the ceiling when emitted in a room, it is generally recommended that, if possible, CO alarms on a wall be placed higher on the wall, at about eye level or higher," says Burton. "If you use plug-in CO alarms, follow the manufacturer's instructions for placement and consider using the highest-placed outlet available in the space for installing the device. Also, avoid outlets that are behind furniture or draperies as they may interfere with the device's ability to detect a problem efficiently."

In short, install CO detectors:

• Outside each sleeping area

• On every level of the home

• At eye level or higher on the wall, when possible

• In an open area (not behind furniture, curtains or drapes)

How to keep them in working order to keep yourself safe

In a nutshell, it's important to actually read and follow the manufacturer's guidelines on your CO detector's maintenance — don't just throw out the pamphlet provided with your purchase. If you don't have the guidelines handy, there are a few maintenance tips you should follow on a regular basis.

"Check and/or change batteries twice yearly, as with smoke detectors," says Dibble. "The most convenient time to remember to do this is when resetting clocks." You also need to test your detectors once a month, according to the manufacturer's directions, says Zevotek. Finally, because the sensors do become less effective over time, you need to replace your monitors according to the manufacturer's directions or every 10 years — whichever comes first.

Also, it's important to understand what the detector's test button does and doesn't test for. "Using a test button tests whether the circuitry is working correctly, not the accuracy of the sensor," says Burton. This is why it's so important to replace your detectors according to the instructions. "In some cases, newer models may have an end-of-life signal that will indicate when the alarm itself needs to be replaced," Burton adds. This may be a helpful feature to consider if you're looking to purchase or replace your detectors.

CO Detectors tested to UL2034

As the experts noted, any CO detector tested to UL2034 should be effective in detecting dangerous levels of CO. However, there are thousands of options on the market. If you need help narrowing down the choices, here are a few that are highly rated by customers.

Affordable with combo-pack options

$20

This is an effective CO detector at a very affordable price, which may be important if you need to outfit your whole house. It is battery powered and does not need to be mounted on the wall, but comes with a mount if you choose to use it. You can also purchase the alarm in combo packs of up to six alarms. 

$20 at FIRST ALERT

Plug-in option

$34

This solid CO monitor is one of the few plug-ins that made it into the top of Consumer Reports rankings for its ability to detect and accurately display CO levels. It has a battery backup and a memory feature that records the highest levels of CO that have been detected. It also has a long cord that enables you to attach it to the wall higher up than the socket it is plugged into.

$34 at FIRST ALERT

CO, air quality and smart device integration

$85

This plug-in, which also did well in Consumer Reports testing, does a lot. Not only does it monitor CO (and sounds an alarm if dangerous levels are detected), but it also monitors other measures of air quality such as unexpectedly high or low temperatures and high humidity. These don't represent an immediate threat to your health, but they can be helpful to keep an eye on. This Kidde alarm also has smart device compatibility to send alerts to multiple family members and can be communicated with through smart speakers such as Alexa. It has a lithium battery backup that's good for 10 years.

$85 at Kidde

Portable for travel or camping

$23

If you travel frequently and stay in hotels, Airbnbs or campers, it may be worthwhile having a portable CO detector with you, especially if you're traveling to areas where you're unfamiliar with state CO detector regulations. This is particularly true if you'll be using fuel-burning heaters or other equipment while you're there. 

There are some nifty, hand-held or clip-on devices on the market that might be perfect for this purpose, but unfortunately we couldn't find one that was rated to UL2034. However, this plug-in CO detector is compact, lightweight, has a rechargeable battery back up and can be easily thrown in your luggage. Just remember to plug it in higher on a wall, if possible. 

$23 at Hakinaku

Includes multiple alarm interconnection

$72

This battery-operated alarm detects both smoke and CO, consistently excels in testing and offers some nice features, including a sound and voice alarm and a memory feature that will let you know if CO levels were dangerous when you were away from your home. It also has the ability to wirelessly interconnect with compatible First Alert alarms so that if you have multiple alarms in your home, when one goes off, they all will.

$72 at FIRST ALERT

Smart alarm

$36

This battery-powered combination alarm, with a lifespan of 10 years, can connect to all your smart devices to give you updates in real time, which is handy if your home is often unoccupied. It also comes with an optional subscription that enables the alarm to communicate directly with emergency personnel, and it is more affordable than many smart alarm options. You can purchase a single alarm, or choose three- or six-alarm packs. 

$36 at X-Sense

No low battery chirps

$46

This is a sleek and straightforward option that you can buy as a single alarm or combine with up to six other alarms. It also offers a 10-year integrated battery, which is the longest you can safely get, guaranteeing that you'll have none of those annoying low-battery chirps over the lifespan of the device. 

$46 at Kidde

Combo smoke and carbon monoxide detectors

It's common now for homes to have alarms that detect smoke, fire and CO, since CO is a by-product of fire. If you are renovating or needing to replace your smoke alarms, too, consider these combo models.

Meet the experts

• Laureen Burton, a chemist and toxicologist with the Indoor Environments Division of the Environmental Protection Agency

• Robin Zevotek, principal fire protection engineer for the National Fire Protection Association

• Melissa Dibble, a spokesperson for the Centers for Disease Control and Prevention

Our health content is for informational purposes only and is not intended as professional medical advice. Consult a medical professional on questions about your health.