Smoke alarms play a vital role in reducing deaths and injuries from fire and have contributed to the almost 50% decrease in fire deaths since the late 1970s. It is estimated that 95% of U.S homes have at least one smoke alarm. Sixty-five percent of reported home fire deaths occurred in homes with no smoke alarms or no working smoke alarms. Properly installed and maintained smoke alarms save lives and protect against injury and loss due to fire.
Source: NFPA's "U.S. Experience with Smoke Alarms and Other Fire Detection/Alarm Equipment" report by Marty Ahrens, April 2007
Most smoke alarms use one of two common sensing systems for detecting a fire.