Smoke detectors prevent burn injuries, smoke inhalation, fire fatalities, and other personal injuries related to fire because they alert house inhabitants that a fire has started. Smoke alarms give victims a warning system so that they can safely escape a burning building, but not all smoke detectors are built the same.

A new study has found that residential photoelectric alarms are a better choice, as they are more likely to remain working. The study, conducted by the Harborview Injury Prevention and Research Center (HIPRC) in conjunction with the University of Washington in Seattle, evaluated ionization alarms as well as photoelectric household smoke alarms and concluded that photoelectric types are far more likely to continue functioning correctly after they are installed. Despite this, most smoke alarms in the US are ionization alarms.

Researchers in the study examined 750 Washington state households and discovered that within 9 months of installation, 5% of the photoelectric smoke alarms and 20% of the ionized smoke alarms did not work. Six months after the initial follow-up, researchers returned to the homes and found a similar trend – many more of the ionization alarms were not working, while most of the photoelectric smoke alarms were working.

The problem appeared to be that home residents were disconnecting or removing the smoke alarm battery. In most cases, this was done with the ionization smoke alarms because they were more likely to go off and sound for reasons other than fire – during cooking, for example. Residents most often cited nuisance and false alarms as the reason they removed the smoke alarm battery.

Both ionization and photoelectric smoke detectors work by detecting particles that are present in combustion. However, ionization smoke alarms work by detecting particles from rapid combustion while photoelectric smoke detectors work by using optical sensors to detect smoldering, slow fires. This makes photoelectric smoke detectors less likely to sound off during cooking.

The findings are significant for a number of reasons. First, the importance of smoke alarms is widely known but the study has shown that the inconvenience of some alarms may be leading homeowners to forgo a potentially life-saving device. Secondly, since many fires begin in the kitchen area, a smoke detector near this area is important. A smoke detector that does not go off during cooking may be an important way to encourage homeowners to keep their smoke alarm functional.