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Smoke and Carbon Monoxide Detectors



  • Properly working, approved smoke and carbon monoxide detectors can help save lives.
  • Smoke detectors can sense and alert you to a fire before you are aware of it.
  • Carbon monoxide detectors sense and alert you to harmful levels of the odorless gas carbon monoxide.
  • Check smoke and carbon monoxide detectors on a regular basis. If you have a battery-operated detector, know when to change the batteries.


How do smoke and carbon monoxide detectors help?

Fires are very dangerous. Most fatal home fires happen at night, while you sleep. You may not realize that a fire has started. A smoke detector can sound an alarm and alert you to a fire in the home in time to escape.

Carbon monoxide (CO) is a colorless, odorless gas that comes from burning fuels such as natural gas, gasoline, oil, kerosene, wood, or charcoal. Carbon monoxide poisoning means that you breathe in too much CO instead of oxygen. Without oxygen, your body tissues are damaged and you could die. A carbon monoxide detector will sound an alarm in time for you to get out before you start feeling sick.

What kind should I get?

Be sure to buy detectors that have been approved by a testing laboratory, such as Underwriter's Laboratory (UL). Check with your local fire department to make sure the alarm meets fire codes. You can get separate smoke detectors and CO detectors, or alarms that combine smoke and carbon monoxide detection.

Some detectors run on batteries. Other detectors are wired directly into the electrical system of a home. Some CO detectors plug in to electrical outlets.

  • The advantages of battery alarms are that they will still work if fire cuts off the electricity to the house. You can put battery alarms in more areas than wired alarms. A disadvantage is that the batteries need to be checked monthly and changed at least every year. Check for low battery reminders in battery-powered models. Replace batteries every 6 months. Many people use the daylight and standard time changes in the spring or fall as their reminder to change the batteries.
  • If you have a wired detector, it can be installed only where wiring is available. It will work without needing to change batteries. However, fires or power outages may mean the alarm stops working. Look for detectors that have a battery backup.

How do I take care of them?

Install, clean, and test the units according to the manufacturer’s directions. Never paint smoke or CO detectors. It’s best to test your detectors once a month.

Test smoke detectors by holding a candle 6 inches away and blowing smoke toward the detector. The alarm should sound in 20 seconds. Some alarms have test buttons, but it’s best to use smoke-testing.

To test a CO detector, use the test button.

Where should I place the detectors?

Install a smoke detector and a carbon monoxide detector on each floor in your home and in each bedroom. Local building and safety codes may require you to have more alarms. For extra protection, you can also put them other rooms and the attic, garage, and hallways.

Since smoke rises, mount smoke detectors high on the wall, close to the ceiling, or on the ceiling itself. Place CO detectors at a height where it’s easy to maintain the detector but out of reach of children. Make sure the detector isn’t covered by drapes or furniture.

Don’t put a smoke or CO detector in the path of air conditioning or heater vents, or too close to windows or doors.

Developed by RelayHealth.
Pediatric Advisor 2015.3 published by RelayHealth.
Last modified: 2015-03-12
Last reviewed: 2015-03-12
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.
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