Why would my fire alarm go off randomly?

Dust and Dirt

Dust that comes from activities like remodeling may set off your smoke alarms. To clean your smoke alarm, open it up carefully, and look inside for dust or dirt. Use a vacuum attachment or electronic aerosol cleaner to remove dust particles.


You might be surprised to learn that some fire alarms do not have the ability to differentiate between particles of smoke and humidity in the air. This is particularly the case with older models. High water content within the air can result in a fire alarm going off for no reason.

Insects in the Air

Smaller flying insects such as flies, mosquitoes and gnats can sometimes enter into the internal workings of a fire alarm. Much in the same way as the moisture mentioned in the previous section, they can cause an alarm to sound. Open up the unit and inspect it to make certain that no small bugs are present.

Fumes and Chemical Odours

This next situation can be dangerous on occasion. There are times when specific chemicals such as ammonia or bleach can result in a false fire alarm; especially if the fumes are concentrated and there is little ventilation. This is obviously a serious event, as some airborne substances can be damaging to your health. If you notice that your fire alarm tends to activate when cleaning, it is a good idea to open the windows in order to increase the ambient ventilation.

Low Batteries

Most alarms will alert you when their batteries are running low. This is actually a safety mechanism, as it is meant to inform the user that the power supply needs to be replaced. It is wise to check the batteries at least once every few months by holding down the “test” button that is found on the majority of detectors. Keep in mind that some batteries are associated with longer lifespans than others.

Steam from a Kitchen or Bathroom

If a fire alarm is located near any of these rooms, it could be activated if a significant amount f steam enters into the air (such as after a hot shower). This is quite normal and no cause for concern. The detector will deactivate once the steam has evaporated.

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