Smoke screening: Which alarm is best?

When consumers go shopping for a smoke alarm, cost is often the deciding factor. But many people don't realize that there are different types of alarms, which may meet different needs.

The two major options are ionization and photoelectric alarms. The ionization devices are less expensive and thus more common. But they can also be purchased now with long-life lithium batteries, which bring the price up to between $10 and $15. That's comparable to the cost of a photoelectric alarm, whose batteries often last only a little more than a year.

Although both alarms will alert residents to fire, the ionization devices are ideal for detecting an open flame, while the photoelectrics are better at noting smoldering fires, such as when a cigarette ignites upholstery, says Richard Bukowski, the senior engineer in the building and fire research lab at the National Institute of Standards and Technology in Gaithersburg, Md.

Bukowski said most fire-safety officials don't believe the differences are great enough to counsel consumers to choose one type of alarm over the other -- they just want consumers to get an alarm and keep it operational. They recommend that all families have them on each level of their homes.

But a study this month in the Western Journal of Medicine points out that sometimes having the wrong type of alarm can impair its use. Researchers gave ionization alarms to all the residents in two villages in Alaska and photoelectric to residents in two others. They found that homes with ionization alarms had eight times more false alarms and were more likely to be disconnected by residents because of the nuisance.

Fire experts cautioned that these results are not exactly applicable to the typical home, since the Alaskan houses were quite small and the alarms were inevitably placed near smoke from cooking areas.

Perhaps the best choice is a combination alarm, which is now available for around $25, Bukowski said.