As we prepare for those dark early evenings when we set our clocks back an hour this Sunday, officially ending Daylight Saving Time, safety officials are issuing their perennial reminder to change the batteries in our smoke alarms and replace our detectors if they are more than 10 years old.

Fire is the second leading cause of unintentional deaths in the home, according to the Consumer Product Safety Commission. More than 3,200 people die in residential fires every year, and more than 390,000 house fires are reported to the authorities.

Furthermore, most house fire fatalities occur between 10 p.m. and 6 a.m., underscoring the need to ensure your smoke detectors are functioning properly so you're awakened if a fire is ignited in your home.

Although 90 percent of U.S. households have smoke alarms, 20 percent of those residences - amounting to some 16 million - are not working, primarily because the battery is missing or dead, a CPSC survey found.

The National Fire Protection Association urges you to replace your smoke alarm if it is more than 10 years old. The NFPA says aging smoke alarms don't operate as efficiently, and they are more likely to trigger nuisance alarms. Plus, replacing after 10 years gives you a chance to install upgraded, more efficient models.

Another pointer - you should replace your alarms if you move into a new home since you probably won't be familiar with the detectors' histories, the group says.

"Simple steps like maintaining smoke alarms and replacing older ones help diminish the possibility of fire deaths in the home," said John R. Hall Jr., NFPA's assistant vice president for fire analysis and research. "Smoke alarms in the home are largely responsible for the decreasing number of home fire deaths over the last decades."

There are several types of fire and smoke alarm technologies on the market. Residential alarms usually use photoelectric technology or ionization technology. Photoelectric relies on an electric current that produces a beam of light.

Ionization sensor technology contains a small amount of radioactive material encapsulated in a metal chamber. It is faster at reacting to fast-flaming fires that produce a lot of smoke.

Both types of alarms contain plastic and electronic circuit boards and in some cases batteries. The amount of radioactive material in the alarm at the end of its certified useful life will be about the same as the time it was bought. The U.S. Environmental Protection Agency's encourages waste reduction and minimization.

Some states conduct an annual round-up of ionization smoke alarms. Some local jurisdictions recommend you return the used alarm to the supplier. If your detector has an alkaline or lithium battery, check with your local recycling program for the best way to dispose of it.

Meanwhile, the NFPA offers these smoke alarm safety tips:

Published: October 21, 2002

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