Carbon monoxide: It’s scentless, colorless, and deadly. According to the Centers for Disease Control (CDC), it kills at least 430 people and sends over 50,000 to the emergency room every year in the U.S. But don’t fear just yet — there are a few safeguards you can rely on to prevent exposure to this noxious gas in your home. By installing a carbon monoxide detector and keeping tabs on your heating systems and all gas- or fuel-burning appliances you are well on your way to lowering your risk.

But first, what is carbon monoxide, and what causes exposure?

Carbon monoxide is formed in environments lacking sufficient oxygen, creating an incomplete burning of carbon-based materials like natural gas, kerosene, oil, propane, and coal. Inhaling these fumes from your car, heating system, or gas-burning grill (among others fuel-burning sources) in confined, windowless, or non-ventilated spaces can cause your body to replace the oxygen in your red blood cells with carbon monoxide. This can lead to symptoms of dizziness, weakness, impaired vision, and confusion, and severe instances can lead to brain damage if CO is ingested in high levels – and that’s if you’re lucky enough to notice. Carbon monoxide earned its “silent killer” nickname because of how hard it is to detect; people who are sleeping or drunk can die of carbon monoxide poisoning without ever exhibiting symptoms.

What safe and unsafe levels look like

This all sounds terrifying, especially when you can’t see, taste, or smell it, but carbon monoxide poisoning is preventable. For starters, have all gas-burning products (hot water heater, furnaces, stoves, space heaters) installed by a professional who can place devices in areas with proper ventilation routes. All said appliances/at-risk spaces also need to be inspected by a professional every year, and never leave your car on idle in an enclosed garage. Of course, you need to install CO detectors, but these devices are not replacements for careful upkeep and inspection of all fuel-burning appliances, like chimneys, stoves, fireplaces, water heaters, etc.

What is a CO alarm?

In a similar fashion to smoke alarms, carbon monoxide alarms alert you when unsafe levels of CO are detected in the air, emitting a loud ringing or beeping sound. Carbon monoxide alarms either come in CO-specific detection devices or combined with smoke alarms, so placement will largely depend on the type of detector/alarm you choose. (Note: Smoke alarms are not substitutes for CO alarms and vice versa.) The CDC suggests buying a detector with a digital readout or screen that allows you to check the concentration of CO in the air at all times and alarms you when levels are too high.

We reviewed the combined smart smoke/CO detector market and found two UL-certified devices that rose to the top, with controls and notifications available to you from anywhere you and your smartphone are. They also self-test and send you specific smoke, CO, or dead battery alerts to alleviate extra guesswork (which could lead to more time scrambling and less time evacuating). Smart smoke/CO alarms might make life easier, but when it comes to choosing a smoke/CO detector, Lisa Braxton, public education specialist for the National Fire Protection Association, says added intelligence isn’t necessary. “Making sure your alarm has been tested by a qualified laboratory is one of the most important steps you can take when choosing an alarm,” Braxton said. “You want to make sure the alarm has been tested for effectiveness and safety by a trusted authority.”

Where do I install CO detectors in my home?

According to Braxton, CO detectors can be installed at most wall heights, as CO mixes with the air. A study conducted by the American Academy of Emergency Medicine (AAEM) found that CO doesn’t pool at the floor or linger in a particular space, but eventually equalizes throughout a room. However, exact placement will depend on the type of CO alarm you choose. If you go with a combined smoke/CO alarm, you’ll want to place the device within 12 inches of the ceiling (or per the manufacturer’s recommendation) in order to detect smoke. Braxton says you won’t lose any CO detection by following these rules, and you will need more than one alarm in your home. The NFPA recommends installing CO alarms outside each separate sleeping area and on every level of the home and in other locations as required by laws, codes, and standards. It’s also important that all detectors communicate and signal alarms together (that way everyone can evacuate).

How to connect your CO detectors:

  • Hardwired vs. standalone systems

    If smart or Wi-Fi connected smoke/CO alarms don’t interest you, you can ensure interconnectedness by choosing a device that can be hardwired to your home’s electrical system. Most states require hardwired smoke/CO detectors.

    Be wary of standalone smoke/CO detectors that are only battery-operated. Unless they use Wi-Fi, these will not communicate with each other. If you do go with this route, be sure to buy several devices to cover the entire house per the NFPA’s recommendation.

Tips to maintaining the efficacy of your CO detector

  • Test smoke/CO detectors at least once every month.
  • If you do have a combined smoke/CO detector, make sure you know what the alarm sounds like for each to avoid any future confusion.
  • Make sure there are no significant obstructions like furniture that could block airflow or function of CO alarm.

If your CO alarm goes off, it’s best to take it seriously. Exit the building or seek an area with access to fresh air before calling your local fire department. If someone is feeling the symptoms of CO poisoning, call 911 and seek medical attention immediately.

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