Message From The Marshal
Smoke alarms have been called “Fire Safety’s Greatest Success Story” but there is still room for improvement: most home fire fatalities still occur at night when occupants are sleeping. Fire is quiet and the toxic gasses have a sort of narcotic effect – impaired judgment, sluggish reflexes, disorientation, etc. Smoke alarms provide the early detection of a fire that could mean the difference between life and death.
As we prepare for Fire Prevention Week (October 9 – 15) this year, I wanted to share some history. The first automatic electric fire alarm was patented in 1890. In the 1930s, scientists began working with early ionization-type smoke alarms. The first low-cost battery-powered residential smoke alarms were developed in the late 1960s. The Los Angeles Fire Department conducted large-scale tests on this emerging technology in 1969 and 1971.
In 1971, residential smoke alarms sold for about $125 each.
Smoke alarm technology flourished in the 1970’s and prices dropped rapidly: solid-state electronics allowed manufacturers to produce smaller units with longer battery life. The optical smoke alarm was patented in 1972. In 1973, Underwriters Laboratories (UL), developed an approval standard for residential smoke detectors.
In 1974, Sears, Roebuck and Company put its name on a battery-operated smoke alarm. The popularity of the Sears alarm prompted other manufacturers to enter the residential smoke alarm market. About 10% of US households owned at least one smoke alarm by 1975. In the late 1970s, residential smoke alarms were first required by law.
Testing conducted by the Illinois Institute of Technology showed that putting a smoke detector on each floor of a home was significantly more effective than putting them only outside bedrooms and at the head of basement stairs. These results were so convincing that the NFPA Standard was changed in 1978 to require this “every level" system.
By 1980, about half of US households owned at least one smoke alarm. Nationwide, home fire fatalities were cut in half by the widespread acceptance and use of these devices. By the early 1990’s, residential smoke alarms were required to be interconnected and located in all sleeping rooms.
The 10-year-lithium-battery-powered smoke alarm was introduced in 1995. In 1999, NFPA began requiring the replacement of smoke alarms after ten years: the sensitivity of detectors changes with time and use, impacting their overall effectiveness. About 95% of US households owned smoke alarms in 2000.
Despite these stunning successes, the following statistics are current:
◦21% of residential fire deaths in the US occur in homes without working smoke alarms.
◦In almost half of these cases, the smoke alarms had missing or disconnected batteries.
◦Another quarter had dead batteries.
Why should I replace my older smoke alarms?
Their sensors deteriorate over time due to the effects of accumulated dust, insects, airborne contaminants, and corrosion. The test button only confirms that the battery, electronics, and alert system are working; it doesn’t mean that the sensor is working.
Several studies have determined that residential smoke alarms fail at a rate of 3% per year of service. Not too bad, right? Read on: at 10 years, that means your smoke alarms have a 30% probability of failure. The Consumer Product Safety Commission (CPSC) reported 20 year failure rates at 46%. An NFPA study found that nearly all smoke alarms fail within 30 years.
The CPSC report also noted that 60% of these failures were the result of dead or missing batteries. Older smoke alarms are more prone to false alarms and it is common (but not prudent) for people to simply remove the power supply in response to these nuisance activations.
What makes the new smoke alarms so much better?
After years of research and development, new residential smoke alarms approved for sale in California have a 10-year non-serviceable battery and a “hush” feature. They should also have a clearly identifiable date of manufacture.
Non-serviceable batteries eliminate the need to replace batteries or to find the one giving that annoying low battery chirp. It also means that people can’t take the batteries of out their smoke alarms in response to nuisance alarms; this is where the “hush” feature becomes more meaningful.
There are also a wide variety of options available.
Ionization Smoke Alarms are best at detecting fast, flaming fires. Ionization units are prone to false alarms from burnt food and steam, so don't mount them near a kitchen or bathroom.
Photoelectric Smoke Alarms are best at detecting smoky, smoldering fires. Photoelectric units are less prone to false alarms from burnt food and steam, so you can install them safely around the kitchen or bathroom.
Dual-sensor Alarms may combine ionization and photoelectric technology or include a Carbon Monoxide detector.
Interconnectability: You can link smoke alarms together so that all units in the house sound an alarm when any single one is triggered. In a home without such wiring, you can buy alarms that interconnect wirelessly.
Special Alarm Types:
Strobe lights for the hearing impaired: Some smoke alarms have an integral strobe light, and some accept add-on strobes.
Voice alarms: Children tend to sleep deeper than adults and may not awaken to a beeping sound. Some smoke alarms allow you to prerecord a voice message. According to one study, many pre-teens who slept through traditional alarms awoke to the sound of their mother's prerecorded voice.
Safety lights: Some smoke alarms provide path illumination, a potential life-saver in the dark.
Security Systems: You can incorporate some of these devices into a system that sounds an alarm outside and inside the house. It can also have a monitoring service notify the police or fire department or even call your cell phone.
Look for the California State Fire Marshal’s seal of approval on the package before you buy. Stick with a single manufacturer/brand for simplicity.