Carbon Monoxide Alarms

What are CO alarms?

Household CO alarms measure how much CO has accumulated. Currently, CO alarms sound when the concentration of CO in the air corresponds to 10% COHb level in the blood. Since 10% COHb is at the very low end of CO poisoning, the alarm may sound before people feel particularly sick. Most CO alarms now have silence/reset buttons and must be immune to elevated ambient levels such as those found in urban areas.

Do I need a CO alarm?

NFPA 720, Recommended Practice for the Installation of Household Carbon Monoxide (CO) Warning Equipment, 1998 Edition, recommends installing a CO alarm in households containing a fuel-burning appliance, fireplace, or in those having an attached garage.

What causes CO nuisance alarms?

Pollution and atmospheric conditions in some areas cause low levels of CO to be present for long periods of time. In fact, these "background" conditions may increase CO to over the 10% COHb equivalency level, causing older CO alarms to sound even though conditions inside the home are not truly hazardous. However, newer alarms have been designed to reduce sensitivities to compensate for these background conditions. Treat all CO alarm warning sounds as real, until it has been verified that there is no threat from equipment inside the dwelling.

If you buy CO alarms:

• Select alarms listed by a qualified, independent testing laboratory.
• Follow recommendations of NFPA 720 and manufacturer's recommendations for placement in your home.
• Install CO alarms in a central location outside each separate sleeping area in the immediate vicinity of the bedrooms. Each alarm should be installed on the wall, ceiling, or other location as specified by the manufacturer's instructions that accompany the unit.
• Call your local fire department's non-emergency telephone number. Tell the operator that you have purchased a CO alarm and ask what number to call if the CO alarm sounds. Clearly post that number by your telephone(s). Make sure everyone in the household knows the difference between the fire emergency and CO emergency numbers (if there is a difference).
• Test CO alarms at least once a month, following the manufacturer's instructions.
• Replace CO alarms according to the manufacturer's instructions, usually about every two to five years.
• Be aware that battery-powered CO alarms may have unique battery packs designed to last approximately two years, compared to batteries used in smoke alarms, which require yearly replacement.