The current state of global smoke alarm legislation
Recent research has analyzed some of the barriers to international adoption of smoke alarm protection
Smoke alarms have been one of the major contributors to improved home fire safety over the past 40 years. Nonetheless, residential fires remain a significant problem and cause approximately 3,000 deaths per year in the U.S. alone. Smoke alarms are designed to detect fires before they become dangerous and to provide sufficient warning to occupants so they can escape. Smoke alarms are essential to ensure the highest level of protection in a residence, but they must be used properly to guarantee maximum safety. As technology evolves and new research is conducted, smoke alarms need to be re-evaluated for effectiveness. The purpose of this project was to investigate international smoke alarm legislation and technology for residential structures and to provide a summary of the findings so that fire protection officials can become knowledgeable about the current state of smoke alarm technology and draft legislation that is more in line with the international de facto standard.
Over the course of the project, types of smoke alarms currently in use (ionization versus photoelectric), the effectiveness of smoke alarm warning tones on certain high-risk population sub-groups, international smoke alarm legislation, and socioeconomic factors that affect such legislation were all investigated. The goal was to review research on smoke alarms as well as the current state of global smoke alarm legislation, in order to compile data and identify possible gaps in international fire protection practices.
Three main methods were used to obtain these data: surveys, interviews, and a literature review. Data on international smoke alarm legislation was obtained through surveys distributed to fire protection experts worldwide. Representatives of 109 different countries, states, territories, and provinces were surveyed, including the United States, Australia, the United Kingdom, Canada, and New Zealand, as well as other countries in Europe, Asia, and Africa. Unstructured interviews were conducted with subject matter experts (SMEs) to provide us with a starting point for our research and literature review. The literature review was conducted, often based on information obtained through our SMEs, to supplement and support the information acquired through interviews and personal communications.
There are two main types of smoke alarms currently on the market throughout most of the world: ionization and photoelectric. Ionization detectors utilize a radiation source (Americium-214) and an electrical circuit to detect invisible particles of combustion ranging in size from 0.001 µm to 3 µm. Smoke enters the chamber and interferes with the measured current, causing the detector to trigger the alarm. Photoelectric detectors sense light from an internal source using photocells. They are sensitive to particles ranging in size from 0.3 µm to 10 µm. When smoke is present, light is refracted and redirected to the light-sensitive photocell, actuating the alarm. It is a commonly accepted fact that ionization alarms respond to flaming fires faster but photoelectric alarms respond earlier to smoldering fires.
There has been much debate in the fire protection community over which of these two types is more effective in reducing fatalities from residential fires. The controversy has been ongoing for years, but it has become increasingly politically charged over the past several months. The dispute stems from the fact that while ionization smoke alarms meet sensitivity and performance requirements, many experts believe that they provide insufficient protection in the case of a typical residential fire. A group of fire protection authorities across the world are leading the push towards requiring photoelectric smoke alarms in all dwellings.
Studies have shown that photoelectric units are more effective at detecting the types of fires that are most likely to be fatal in homes: smoldering fires. One study reported that photoelectric smoke alarms respond more rapidly in three out of four likely residential fire situations: a smoldering fire with the alarm in the room of ignition, a smoldering fire with the alarm outside the room of ignition, and a flaming fire with the alarm outside the room of ignition. The only case in which the ionization alarm responded first was when the alarm was in the room of ignition of a flaming fire. Even then, the photoelectric alarm still provided the occupants with enough time to escape safely.
After a smoke alarm has detected a fire and sounded the alarm signal, the occupant must respond accordingly for the device to be of use. Recent research has shown that the current warning tone of standard smoke alarms is often insufficient to trigger the desired response from certain high-risk groups. Young children, the elderly, those with hearing impairment and/or high frequency hearing loss, and those who are alcohol impaired are at risk of sleeping through the standard tone.
The standard warning tone used in current smoke alarms is a sine wave with a frequency between 3000 Hz and 4000 Hz. It is easily distinguishable from background noise and therefore is a good notification of a dangerous situation for those who are awake. However, studies have shown that this signal is less than optimally effective for waking sleeping occupants. The most effective signal is a 520 Hz square wave, because of its additional energy at odd harmonics of the fundamental frequency. Unfortunately, size and power constraints prevent this technology from being utilized in standard smoke alarm units; future research will be necessary to make this signal useable in such a small device.
There are numerous factors and variables that influence the specific smoke alarm needs of a residence, especially the social and economic status of the region in which it is located. The prevailing lifestyle, heating fuel, and cooking methods, among other things, must be taken into consideration when recommending or requiring a specific type of smoke alarm for a residence. For example, in many developing countries people cook with coal, which is likely to trigger false alarms if a smoke alarm is present. This presents a problem because nuisance (false) alarms, which most often occur with ionization units, have been shown to be one of the primary reasons for homeowners to disable smoke alarms, rendering them useless. In addition, functionality is often less of a concern to the average buyer than affordability and cost, since most buyers are unaware of the different technologies available. In most cases, ionization alarms are less expensive than photoelectric, and are therefore the more popular of the two types.
The economic climate of a region is especially important when considering legislation requiring smoke alarms. It does no good to require smoke alarms in a country where nobody can afford them. The difference in smoke alarm affordability across the globe is enormous. It takes approximately a quarter-hour of work in the United States or Australia for an average citizen to be able to afford a smoke alarm, but over 75 hours of work in China. In nations where smoke alarms are an unobtainable luxury to most citizens, alternative methods of protection need to be considered.
Despite the variations in local circumstances, there is still a universal need for fire protection. Many regions around the world have legislation making smoke alarms compulsory in most or all dwellings. Of the 109 surveys addressing this question that we distributed, 76 responses were received. Only 29 percent of responding countries have enacted nationwide smoke alarm legislation. Of the eight Asian countries that responded, only one, Japan, has legislation. Europe, however, is relatively aggressive with smoke alarm legislation, with five out of the ten surveyed having legislation. Australia, the United States, and Canada do not have any nationwide legislation, but they have national provisions that can be adopted by individual states, territories, or provinces. There are very few regions that specify smoke alarm type, as only three of the 76 returned surveys stated that photoelectric units are required.
The most significant problem identified among regions with smoke alarm legislation is a lack of enforcement and compliance monitoring. Penalties for non-compliance should be stronger than they currently are, and inspections should be conducted on a more regular basis rather than only when an occupancy permit is issued or a home is sold.
Through our research, we have found that it is difficult, if not impossible, to make generalizations about the “ideal” smoke alarm arrangement for residences on a global level. For developed countries such as Australia and the U.S., the “ideal” smoke alarm is photoelectric, hard-wired with a battery backup, and interconnected. However, the number of factors and variables that can affect recommendations for type and proper use of smoke alarms are so great and vary so much for differing situations, it would be a gross oversimplification to make any blanket statements on the subject. Lifestyle differences like cooking methods, heating fuel, climate, housing style, and economic climate are only a few of the variables that must be considered.
By Timothy Manchester, John Meklenburg, Kemal Moise, and Brian Potts.
Over the Summer Autumn period students from Worchester Polytenic Institute (New England USA) conducted research into smoke alarms on behalf of FPA Australia.
Contact: By Timothy Manchester, John Meklenburg, Kemal Moise, and Brian Potts.
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