Household smoke alarm technology has been stagnant for years. The main methods of detection are photoelectric and ionization. Each triggers an alarm when they detect products of combustion. These technologies have individual strengths. When combined, they can offset each other’s weaknesses. However, both technologies are susceptible to nuisance alarms – primarily from cooking and steam. According to National Fire Protection Association (NFPA) statistics, most home fire deaths occur when smoke alarms are not present or do not work. When a smoke alarm fails, it’s usually the result of being disabled. Nuisance alarms are the leading cause of disabled smoke alarms1. Thus, reducing nuisance alarms would not only reduce frustrations, but also save lives.
Smoke alarms haven’t changed much throughout the years, but home contents have. Over the past few decades, the use of man-made synthetic materials (such as polyurethane foam) has become widespread. When compared to traditional materials, synthetic materials burn faster and hotter. This greatly reduces the time between fire detection and the onset of hazardous conditions. As the amount of synthetic materials in households increases, so does the need for reliable detection and notification.
By 2010, NFPA realized the importance of reducing nuisance alarms. Thus, the 2010 edition of the National Fire Alarm and Signaling Code (NFPA 72) added language to restrict the placement of smoke alarms near stationary cooking appliances.
The requirements in NFPA 72 are not adopted in all jurisdictions. Also, adopted codes are not always enforced. As a result, NFPA added a new requirement to the 2013 edition of NFPA 72. The new requirement aimed to reduce nuisance alarms by modifying test standards. Effective January 1, 2019, newly installed household smoke alarms had to be listed for resistance to common nuisance sources. This requirement was also in the 2016 edition of NFPA 72. However, it became clear that manufacturers needed more time to comply with the above-mentioned requirement. As such, the 2019 edition of NFPA 72 requires the same listing to resist common nuisance sources but postpones the effective date to January 1, 2022 (reference Section 22.214.171.124(6) in NFPA 72-2019 for specific language).
It’s exciting to know manufacturers are close to marketing smoke alarms that are resistant to nuisance sources. Currently, smoke alarms are being tested for such a listing. Instead of just knowing if smoke is present, the next generation of smoke alarms should be able to determine the composition of smoke particles present to decipher what’s burning and if it’s a threat. The exact science behind the next generation of smoke alarms is complex and closely guarded by each manufacturer. In time, it will be better understood. However, it’s the result that matters. Next generation smoke alarms will reduce the frustration of nuisance alarms. In turn, people will be less likely to disable their household smoke alarms. This will save lives.
Written By: Mark R. Richards, PE
1 NFPA. (September 2015). Reports and statistics about smoke alarms. https://www.nfpa.org/Public-Education/By-topic/Smoke-alarms/Reports-and-statistics-about-smoke-alarms