Congratulations! You have taken an important step in protecting your family from a silent killer. Carbon monoxide poisoning is responsible for over 500 deaths and 1,5000 emergency room visits annually in the United States, and has become the leading cause of unintentional poisoning deaths (according to the CDC).  

Many newer homes have carbon monoxide detectors installed and hard-wired when building the home.  For those with older homes, or in states where it is not required, inexpensive detectors can be purchased at large retail outlets or home improvement stores. These detectors either plug directly into an outlet (with a battery backup), or rely on batteries.  In these cases, it is up to the home owner to decide where to place the detector.

When your carbon monoxide detector alarm goes off, it is important to immediately respond to the situation - leaving the house and calling the fire department if there is any reason to suspect carbon monoxide in the house (such as an alarm going off!).  Since carbon monoxide gas is colorless and odorless, there is no margin for error here.  

Carbon Monoxide DetectorCredit: By Sideroxylon (Own work) [Public domain], via Wikimedia Commons

This means that fire departments must respond to every call for a carbon monoxide detector alarm going off. Fortunately, most of the time this catches the situation before anyone actually becomes sick from carbon monoxide poison, but many times the responders do not detect any increased levels of carbon monoxide in the home using their portable detectors. This might be because the home owner aired out the house (opening windows and doors) before they arrived, but more often it is the result of either a false alarm (dust and insects on the sensor can cause the detector to become extra sensitive and produce false alarms) or it is the result of activities of the home owner - running a leaky space heater, forgetting to open the flue on the fireplace, etc.

These nuisance alarms not only cause wasted time and money for responding fire departments, but much inconvenience on the part of the home owner, as they waste a few hours waiting for the house to be inspected.  Many times these false alarms are simply due to improper placement of the detector - putting it too close to places with common low levels of carbon monoxide or other elements that can interfere with the sensor.

Be sure to check on the placement of your detector today!


1. In the garage

This is an obvious one, but you would be surprised at how many times it has happened! Simply pulling your car into or out of the garage could easily set off your carbon monoxide detector.  There have even been cases where having the detector too close to the garage has set off the detector while warming the car in winter (with the garage door open).  

On the other hand, you should place a carbon monoxide detector in the room above the garage, particularly if being used as a bedroom.  It is possible for smaller levels of carbon monoxide to build up (and rise when heated just like air) and cause the person sleeping there to develop over time low-level carbon dioxide poisoning symptoms like headaches and nausea.

2. Near a fireplace

Any source of an open flame will produce carbon monoxide, including both wood-burning and gas-powered fireplaces. Blocked chimneys and closed flues will cause carbon monoxide to flow into the room - this is a primary reason you should have a carbon monoxide detector in the first place. But even with the flue open and a clean chimney, some amounts of carbon monoxide still enter the room. These low levels are not enough to cause health issues, but an overly sensitive monitor placed too close to the fireplace could set off the alarm. 

3. Near a furnace or water heater

Carbon monoxide detectors should be placed at least 15-20 feet from any fossil fuel burning source - and gas furnaces and water heaters are exactly that.  Keep the detector out of the utility room, or the laundry room as well.

4. In the kitchen

Just like the furnace, a gas stove can set off the detector as a small amount of carbon monoxide is released when turning it on.   Cooking with alcohol can increase the incidence of nuisance alarms as well. Turning on the vent while cooking can help circulate the air, and regular cleaning of the oven and stove-top can also decrease the incidence of false alarms. 

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5. In the bathroom

Places of high humidity can cause nuisance alarms as well. The steam from the shower is a prime example of high humidity. Newer detectors have been developed with photoelectric sensors are less sensitive to these situations.

6. Near the cleaning supplies

Cleaning supplies are strong chemical compounds that can emit vapors strong enough to set off the alarm on a carbon monoxide detector.   If you are storing these outside of your kitchen or garage, such as in a hall closet, be sure your detector is not placed too close to that closet.

7. Near ceiling fans

Carbon monoxide is nearly the same "weight" as air, so placing a detector high or low in a room is not as important. But ceiling fans, heat vents, cold air returns and even open windows can cause the alarm not to work as designed. 

8. Near candles or automatic air fresheners

Just like a fireplace, candles are an open flame and can emit small amounts of carbon monoxide even with proper use. Perfumes and automatic air freshioners, and even hair spray, have been know to cause nuisance alarms. 

9. Near humidifiers

Some homes have a whole-house humidifier, but many people still use the smaller, portable humidifier for single rooms. Humidity can cause false alarms in these detectors, so either keep the detector in a different room, or be sure the detector instructions clearly state  it is not sensitive to humidity.

10. Near smokers

Cigarette smoking does create a low-level of carbon monoxide. While this may not be enough by itself to set off the alarm, having several smokers in the house may.  If you allow smoking in your house, be sure to keep the detector in a hallway or other area where smokers are less likely to be stationary for any length of time.

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Having a carbon monoxide detector is worth it, even if you have to deal with nuisance alarms!

All of these locations have the potential to cause false alarms in carbon monoxide detectors. It is extremely important, though, to take it seriously every time the alarm sounds. Go ahead and evacuate the house and call the fire department - they will assure you that you are not the only one! Discuss the current placement of your detector with the responders, they are trained to understand how the alarms work and can offer tips on ways to lessen false alarms while still protecting your family.  Never be embarrassed to call - it is always better to be safe than sorry!