That smoke detector outside your bedroom door could be giving you a false sense of security. It might not sound quickly enough to get you up and out if there’s a fire when you are asleep.
It feels like heresy to question the value of smoke detectors. Clearly, these are life-saving devices. But some of the nation’s firefighters are doing just that. They’re on a crusade to get people to change the type of alarms found in most homes.
Smoke alarms 101
House fires will kill about 3,000 Americans this year. Surprisingly, more than a third of the victims will have at least one working smoke detector in their home or apartment.
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How could this be?
As it turns out, not all smoke alarms are the same.
There are two basic types of detectors: ionization and photoelectric. Ionization models are quicker to spot flaming fires. Photoelectric models react more quickly to smoldering fires, the kind caused by a cigarette on the couch or an overloaded extension cord. These smoldering fires produce toxic gases that can kill people sleeping in the house before there are any flames.
While any smoke detector is better than nothing, a growing number of experts favor photoelectric or dual-mode alarms to guard against both fire and smoke.
Nine out of 10 homes in the U.S. have ionization alarms. There are two reasons for this. They are cheaper to buy, and fire departments across the country have given them away for decades.
Comparison tests show differing results
Many safety experts believe either type of smoke detector is adequate, as long as the unit is working properly. Six years ago, the Commerce Department’s National Institute of Standards and Technology conducted an extensive test. The report said both ionization and photoelectric detectors “consistently provided time for occupants to escape from most residential fires.”
Others disagree. For almost 20 years, B. Don Russell, a professor of electrical engineering at Texas A&M University, has studied smoke alarms. He uses a full-scale test facility to see how the detectors respond to different fire conditions and various materials. Russell says there is little difference between the two types of alarms when there’s a flaming fire, but his tests show ionization alarms are dramatically slower when it comes to smoldering fires.
“When you’re asleep, you need the earliest possible warning to get out and you do not get that with just an ionization detector,” Russell says. “So if you were going to pick a single smoke detector to put in your home, pick a photoelectric detector.”
Building codes changing
In Massachusetts, new or renovated homes or apartment cannot rely solely on ionization alarms for fire protection. If a detector is within 20 feet of a kitchen or bathroom, it must be photoelectric. It took Boston’s deputy fire chief Jay Fleming years to get the law passed.
“Any smoke detector is better than nothing.” Fleming says. “I don’t want anyone to throw out what they have. But there’s an alternative out there that for only a few dollars more works better than what most people have in their homes.”
In Vermont, all new homes and those sold to new owners must have photoelectric detectors on every floor. State lawmakers passed the law after a tragic apartment fire in the city of Barre claimed the lives of four children and their mother in 2005.
Firefighters say the ionization smoke alarms didn’t go off even though the building was filled with smoke. As part of the investigation, the detectors were checked and found to be working.
To find out how this happened, Barre firefighters did some experiments, testing both ionization and photoelectric alarms. They used a soldering iron stuck in a couch. The photoelectric alarms sounded in about 10 minutes. It took an hour and six minutes for the first ionization alarm to go off.
“If you and I had been sitting a desk next to each other, I wouldn’t have been able to see you,” Lt. Mike Cetin told me. “You think you’re well protected with an ionization smoke detector, when you’re not really protected that well at all.”
“If we could wave a magic wand right now and get rid of all the ionization smoke alarms and replace them instantly with photoelectric smoke alarms, we would cut out fire deaths in this country by more than 50 percent,” McGinn says.
Tests also show photoelectric alarms are less prone to nuisance alarms. Studies show that as many as a third of all smoke alarms in U.S. homes are disconnected, which could account for hundreds of fire deaths each year.
People often remove the batteries when cooking or moisture from the bathroom causes the alarm to sound when there’s no danger. You want that alarm to go off when there’s a threat to your life, not when you’re cooking a steak.
Some think the push for photoelectric detectors is misguided. The National Fire Protection Association says “either type of smoke alarm will provide sufficient time for escape for most people for most fires of either smoldering or flaming type.”
First Alert, a major manufacturer, takes the same position. Kidde, the other big smoke alarm manufacturer, goes one step further. Spokesperson Heather Caldwell says, “Banning a proven technology can truly limit innovation and could be a disservice to consumers.”
Even Underwriters Labs says the science doesn’t support outlawing ionization detectors.
The bottom line: Consider dual detectors
Many safety experts recommend a smoke alarm with both an ionization and photoelectric sensor. These combination models, which are widely available, guard against both flaming and smoldering fires. That way you’re protected no matter what type of fire you have.
Consumer Reports recommends replacing ionization units with these new dual sensor models. The editors also recommend alarms that are wirelessly interconnected, especially if you have a multilevel house. That way if one goes off (say in the basement) they all sound throughout the house.
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