A carbon monoxide detector will always protect my family from CO issues. (Wrong!)

Carbon Monoxide Detectors

The two key words that are problems with this myth are “always” and “protect”.

Always Doesn’t Mean “Every Time”

If the concentration of carbon monoxide is rising quickly and confined to the basement, the CO detector located near the first floor bedrooms (the recommended location) will never sense it. Sending your kids to the basement to play could turn out to be a bad idea. The point is … have detectors in multiple locations.

The ONLY thing a CO detector does is sense chemicals in the air surrounding it. The top of the line detectors sense only carbon monoxide and do not alarm when other gasses are present. Less expensive detectors may alarm due to fumes from nail polish, hair spray, aerosol cleaners, spray paint, refrigerants and even cooking sprays.

The word “protect” is another issue.

Because of the frustrations experienced by many CO detector owners and fire-departments caused by nuisance alarms, UL (Underwriters Laboratories) decided to change the standards in UL-2034 (the standard for detector performance.) The new UL-2034 benchmarks require a CO detector to sense low levels of CO (30 ppm) and not alarm for a minimum of 30 days! It must also ignore levels up to 70 ppm for at least an hour.

If you have a family member with breathing problems, or have infants or elderly in the home, you need to do more investigation into acceptable carbon monoxide levels. People with these types of issue have been known to be affected by low-level CO exposure.

Also note that CO exposure may cause different reactions from different people. Some folks appear unaffected at levels that make other people nauseous. (A lot of this information is covered in Carbon Monoxide Myths.)

Another problem that is NEVER discussed … is CO detector fouling.

Some makes of detectors that have been exposed to high levels of refrigerant (when your home air-conditioner or refrigerator is repaired) become worthless. Their sensors are fouled by refrigerant and will no longer sense carbon monoxide. The electronic circuitry is intact, but the chemicals that make up the CO detector’s sensing mechanism no longer function. The higher quality detectors will provide an error indication or alarm to signifiy that there is a problem. The cheap detectors … they just sit there.

Here’s a a couple of good videos that illustrate the point about how carbon monoxide detectors react differently. 


Good Method to Test Carbon Monoxide Alarms

Note that this really isn’t a valid test because the
CO detector needs to sense a constant level of CO
before it goes into alarm. They are designed to track
but ignore low CO levels for specific periods of time.
But, it is also why you can not rely soley on an alarm.

Old Carbon Monoxide Alarms Don’t Work!!

If your carbon monoxide alarm is over five (5) years old, it is no longer reliable. Most manufacturers warn owners to replace their alarms after five years. Beyond that point the sensing elements become non-responsive and may not alarm in the presence of carbon monoxide. The test button will work, but the alarm will not sound an alert to carbon monoxide.

Here’s a story from Chicago’s CBS Channel 2 about a random test of carbon monoxide alarms. They were surprised to find that 7 of the 10 alarms that they tested did not alert when exposed to high concentrations of CO.


Pritzker Olsen Attorneys understand the possibility of inoperative CO detectors

A Few Words from the EPA on Carbon Monoxide Detectors

Carbon Monoxide Detectors are widely available in stores and you may want to consider buying one as a back-up — BUT NOT AS A REPLACEMENT for proper use and maintenance of your fuel-burning appliances. However, it is important for you to know that the technology of CO detectors is still developing, that there are several types on the market, and that they are not generally considered to be as reliable as the smoke detectors found in homes today. Some CO detectors have been laboratory-tested, and their performance varied. Some performed well, others failed to alarm even at very high CO levels, and still others alarmed even at very low levels that don’t pose any immediate health risk. And unlike a smoke detector, where you can easily confirm the cause of the alarm, CO is invisible and odorless, so it’s harder to tell if an alarm is false or a real emergency.

Check the Date Code

The date code for most alarms is either stamped or printed on a label located on the back of the alarm. Most manufacturers suggest replacing the alarm if it is more than five years old, based on the date code. Some manufacturers suggest replacing the alarm after 10 years. Check with the manufacturers’ websites. All manufacturers say to replace the alarm if there is no response when the test button is depressed for 3 seconds. 

Reliable, Tamperproof Carbon Monoxide Alarm with 5-year battery

Here’s a carbon monoxide detector that solves a number of issues that frustrate homewoners. It has a five-year lithium-ion battery protected in a tamper-proof compartment. The wall-mount is also tamper proof (to keep kids and tenants from taking them down.)

The detector uses a state of the art, water-based, electro-chemical sensor and circuitry that tracks the current CO level, peak level and duration. Tapping the test/reset button will show the current carbon monoxide concentration and the peak CO level.


  ProTech 7035-SL Lithium
Battery Powered
Carbon Monoxide Alarm
with Display