Jane Perkins

Smoke alarms save lives and are critical in protecting families from the devastation of home fires. They provide early warning of fire and allow for additional time to escape before smoke and flames obstruct and hinder your exit. However, there are times when smoke alarms sound when there is no fire. Residents want to know what causes the smoke alarm to sound in their homes if there is no fire.

Firefighters urge residents to never ignore the sound of smoke alarms. If your alarm is sounding, exit your home immediately, and call 911. These early fire detection devices can sense hidden fires, such as electrical ones, before people can.

Statistics from the National Fire Protection Association show that an average of three out of every five residential fire deaths resulted from fires in homes without functioning smoke alarms. The death rate was more than twice as high in homes that did not have working alarms. Simply put, the risk of dying in a residential home fire is cut in half in homes with working smoke alarms.

But thankfully, there are many times when that warning sound emanates as the result of a smoke alarm sensing something besides smoke. Understanding how a smoke alarm works will assist you with placement and maintenance of the alarms, and reduce the number of false alarms in your home.

Smoke alarms have one of two types of sensors. Ionization alarms contain a chamber with two plates that generate a small, continuous electric current. When smoke enters the ionization chamber, the smoke particles disrupt the current flow, which triggers the alarm. Photoelectric alarms use a light beam and receptor. When smoke is present between the light and receptor, the change in light on the photocell sensor triggers the alarm.

Smoke alarms are meant to be sensitive so that they are effective. Their purpose is to catch a fire in your home before it becomes life-threatening. However, if you are faced with persistent alarm activations without the presence of fire, you might want to reconsider the placement of your smoke alarms. Smoke from burnt food can often be enough to set your smoke alarm off unexpectedly. In fact, popcorn, bacon, or overly cooked remnants at the bottom of ovens and toasters seem to be particularly troublesome for many local residents.

Humidity often mimics the effects of smoke and can cause smoke alarms to activate. If you know that you will experience high humidity or steam near your smoke alarm, try using fans or windows to dissipate the steam. In bathrooms, the overhead fan is usually sufficient to remove the steam from a shower. In kitchens, you might consider a vent above a stovetop or opening a window near the cooking area.

Dust can also activate alarms because it reflects the light particles, similar to smoke, which gives you a false fire alarm. Local firefighters frequently respond to alarm activations caused by contractors working in homes. The dust raised by sanding or cleaning mimics smoke and activates the alarm.

Insects love those dark corners in your home and may take up residence in your smoke alarms. Recently firefighters responded to a smoke alarm activation in a local business, and after an investigation of the establishment, they determined that baby spiders hatched in the area near the alarms. The alarms were installed properly and were working appropriately, but the hatchlings interrupted the light beam inside the device, so the alarm sounded.

Smoke alarms save lives. When properly installed and maintained they play a vital role in reducing fire deaths and injuries. If there is a fire in your home, smoke spreads fast and you need smoke alarms to give you time to get out. 

Remember, when the smoke alarms sound, they are doing their job. When you hear the alarm, leave your home immediately, call 911 from outside using a cellphone or a neighbor’s phone, and meet your family at a prearranged meeting place to determine that everyone is safe. Your local firefighters will rule out fire first and then determine what caused the alarm.

For more information about maintaining your smoke alarms, call your local fire department. Firefighters are more than happy to provide guidance on where to place the devices and how to clean them.

This column was written by Jane Perkins, fire safety specialist for the Rhode Island Southern Firefighters League and captain of the Watch Hill Fire Department. If you would like to see a question answered in this column, please email her at askafirefighter@yahoo.com.

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