The facts are clear that smoke detectors in your home are important. In fact, not having a functional smoke alarm doubles your chances of dying in a house fire. And, two-thirds of all fire-related deaths happen in homes without functional smoke detectors.
So, if you’re like 96% of the nation’s homes, you have at least one smoke alarm. And because you are concerned about minimizing fire risk you change the battery twice a year when we set the clocks back and forward. You can rest easy knowing that you’re protected, right? The answer is maybe and maybe not. It all depends on the type of smoke alarms you have.
The Two Types of Smoke Alarms
Most residential smoke alarms utilize either ionization or photoelectric technology. And while you may think that “a smoke alarm is a smoke alarm” there are crucial differences in the ways these two technologies respond to fires.
About 90 percent of installed alarms are ionization type smoke detectors which are typically more responsive to fast flaming fires such as stove top or cooking fires. These types of fires often occur when people are awake and can more easily escape.
Photoelectric smoke detectors are typically more responsive to smoldering fires in living spaces where furniture, mattresses and synthetic materials generally burn more slowly with a long period of smoldering before they erupt into open flames. These fires often start overnight when occupants are likely asleep.
Here’s the critical difference between these two types of smoke detectors:
On average, ionization smoke detectors respond about 30 seconds faster to an open-flame fire than photoelectric alarms and in a flaming fire there can be little time to spare.
In a smoldering fire, however, ionization units may respond on average 30 to 60 minutes slower than a photoelectric unit. In some cases, ionization smoke detectors may not always alarm even when a room is filled with smoke from a smoldering fire.
Photoelectric detectors can provide a lot more warning time than ionization detectors in a smoldering fire. While smoldering fires account for only about 12 percent of fires, they also account for more than half of fire-related deaths and a third of fire-related injuries (most residential fire fatalities occur at night and are the result of smoke inhalation).
Changes in building materials and furnishings over the past decades have reduced the time available for safe escape in any fire so having proper warning of either a smoldering fire or an open flame fire as early as possible is absolutely critical.
Another Problem with Ionization Smoke Alarms
A recent Alaskan nuisance alarm study indicated that 92% of homes with ionization smoke alarms experienced nuisance alarms compared to only 11% with photoelectric smoke alarms.
The reason this is important is that occupants disable ionization smoke alarms by removing the batteries because of frequent nuisance alarming. And a disarmed smoke alarm is, obviously, useless. In fact, homes with non-functional smoke alarms account for close to two-thirds of all fire-related deaths.
What Type of Smoke Detectors Should I Have?
You should perform your own research before making a final decision, but consider that the Consumer Products Safety Commission says that best protection when it comes to smoke alarms is to:
- Install a working smoke alarm on every level of the home, outside sleeping areas, and inside bedrooms
- Install both ionization and photoelectric type smoke alarms
- Install interconnected smoke alarms
- Install smoke alarms using house wiring with battery back-up
The data is clear that having both ionization and separate photoelectric smoke alarms provides the best protection from both fast moving flaming fires and smoldering fires.
Consider that the National Fire Protection Association, Consumer Products Safety Commission, United States Fire Administration, National Institute of Standards and Technology and the National Association of State Fire Marshals all recommend having both types of smoke alarms installed.
Additional Features to Consider in Your Smoke Alarm
Interconnected Alarms: This type of alarm causes all the interconnected alarms in the home to alert if one has detected smoke. For example, if a fire starts in the basement all the alarms in the house, including those on the upper bedroom level will sound which may give occupants additional escape time. Interconnected systems can be hard wired or are available using wireless technology.
Talking Alarms: There are now talking alarms that not just sound an alarm but “speak” to you alerting you to the detected hazard.
Kids and Your Escape Plan
Remember that many children will sleep through smoke alarms! Do not assume they will awaken and find their way out of the house. Make sure everyone in your family knows how to escape when the smoke alarm goes off, whether they are awake or asleep.
There are numerous organizations that can be relied on as resources for additional information and research:
Consumer Products Safety Commission www.cpsc.gov
National Fire Protection Association www.nfpa.org
United States Fire Administration www.usfa.fema.gov
National Institute of Standards and Technology www.nist.gov
What Type of Smoke Detector Do I Have Now?
To identify an ionization alarm, look for a model number that includes the letter “I,” Americum-241 or any mention of radioactive material. A photoelectric alarm often identifies itself as “photoelectric” or sometimes with a capital “P” somewhere on the device. If your smoke alarm is subject to frequent nuisance tripping it’s almost certainly an ionization alarm.