Waking up to the Truth
The idea of using a smoke-detection signal to protect people as they sleep is terrific. And there’s no doubt that smoke alarms have saved many people from major injury or death. Perhaps because of such success, fire-safety campaigns throughout the world have focused on promoting the installation and maintenance of smoke alarms as their major educational initiative.
But now it’s time to look more closely at the situation and ask some hard questions about smoke detectors. For starters, are smoke alarms as effective as they could be? Is there room for improvement? During a fire, who’s likely to wake up and who isn’t? Are we too complacent about the effectiveness of smoke alarms? The research I’ve conducted suggests we put far too much faith in the ability of smoke alarms to reliably awaken sleepers being threatened by fire. Let’s take a look at current beliefs about smoke detectors and examine the facts.
Myth: We can always rely on smoke alarms to wake people up.
Personal Factors
Age. It’s true that most people over age 18 will wake up to a smoke alarm signal, even if it’s sounding in the hallway and the bedroom door is closed—provided none of the other personal or situational factors are exerting a major influence (see below).
However, sleeping children are much less likely to be roused, and those ages 11 and younger are especially at risk. This is because children get more deep sleep than adults and also because their deep sleep tends to be deeper than that experienced by adults. When we first started testing whether children would wake up to a smoke alarm, many parents said they knew nothing would wake their little ones. As any parent knows, seeing children remain blissfully asleep while a smoke alarm on the ceiling above their bed shrieks continuously is a memorable and unsettling experience.
As children move into the second decade of their lives, the likelihood of them awakening to a smoke alarm increases. (These rates are much lower if the smoke alarm is located in the hallway, as compared with the bedroom.)
At the other end of the age scale, we find that the elderly are also at increased risk for not awakening to an alarm signal. The main reason is high-frequency hearing loss. It’s likely that at least 25 percent of those aged 60 and older would not be awakened by a hallway alarm—and that risk increases with age. In addition, the elderly are four times more likely to be regularly taking sleeping pills than the rest of the adult population, and this certainly increases their vulnerability in a fire situation.
Deep Sleep Versus Light Sleep. Most fire fatalities occur in the first half of a night’s sleep (for most sleepers, that’s typically between midnight and 4 a.m.). Do more fatalities occur then because that’s when most fires within the sleeping period start—or because people are more deeply asleep during that time? Or is it because of both? Overall, people are less responsive to sounds that occur during the first third of the night, and equally responsive in the second and final thirds of the night. Also, the time needed by a sleeper to wake up is longer if the person is in the deeper stages of sleep, which are associated with the first two to three hours of sleep.
Individual Differences. For reasons we don’t fully understand, some adults are just much harder to wake up than others. In one study, some people woke to the quiet 39-decibel tone (which is almost at the same volume level as background noise), while others in the same age group and stage of sleep needed an ear-piercing alarm registering 121 decibels.
Sleep Deprivation. There’s no doubt that a person recovering from sleep loss is harder to wake up than someone who is regularly getting a sufficient amount of sleep. How much harder depends on that particular person and his amount of sleep loss. Certain groups of people are especially at risk; adolescents and shift workers are known to often be chronically sleep-deprived.
Sleeping Pills. It’s easy to understand why sleeping pills make it harder to wake up to an alarm. In fact, sleeping pills are actually designed to reduce a person’s responsiveness to both external stimuli (house noises, a snoring partner, etc.) and internal stimuli (such as worry and stress). During the two to three hours after intake, when sleeping pills are working best, people are only half as likely to wake up, as compared to people who didn’t take any pills.
Alcohol. This is the big unknown in terms of how effectively smoke alarms wake people. However, we do know that alcohol causes changes in brain-wave activity, increasing deep sleep in the first few hours of sleep. And, as you would expect, it’s harder for any individual to be roused from deep sleep than a lighter state of sleep. Given that some studies suggest that about one-half of all fire victims were intoxicated, the link between alcohol intake and the ability to wake up to an alarm needs careful examination. Marijuana smoking also seems to produce a similar increase in deep sleep during the first hours of sleep.
Situational Factors
The chance of waking to an alarm is also dependent on several situational factors:
Location of Alarm. Obviously, smoke alarms are most likely to wake up people if they are loud enough to be heard. To that end, alarms should be located in the same room as the sleeper (so that the pillow volume measures between 80 and 92 decibels). Putting alarms in the hallway and then closing the bedroom door reduces the pillow volume to between 51 and 68 decibels. A drop of some 30 decibels makes a big difference in waking vulnerable sleepers. We have already shown that it reduces the likelihood of six- to 15-year-olds waking up from 50 percent to 6 percent.
Background Noise. An air conditioner can create a background noise level of around 50 decibels. With such an air conditioner operating in a bedroom, a hallway alarm of 51 to 68 decibels may be virtually inaudible, let alone loud enough to wake most people up. Living on a busy street with high levels of traffic noise may be even more of a problem than air conditioner noise. This is because the sleeper constantly exposed to such noises learns to block out intermittent sounds, such as those made when cars and trucks accelerate and change gears and honk their horns and when emergency vehicles ride by with sirens wailing. Thus another intermittent sound—a beeping alarm—may blend into the generally noisy blur.
Studies Under Way
We are currently in the middle of collecting information comparing how people wake up to three sounds: the T-3 signal (pattern of three standard signals of defined length and interval, but not frequency), the older style of modulating smoke alarm signal (which uses two frequencies), and a voice alarm. The female voice speaks messages such as “Fire! Danger! Wake up!” So far, our research shows the voice alarm is waking young adults up at lower volumes than the other two signals. The T-3 alarm requires the highest volume to be heard and understood.
We’ve also been comparing how young children wake up to a voice alarm versus the modulating alarm. At this stage of our research, an 89-decibel female voice alarm has reliably awakened 97 percent of six- to 10-year-olds (when testing the responses of 12 children to a 1 a.m. signal), as compared with only 29 percent of those children being reliably awakened by the modulating smoke alarm signal. The voice alarm also wakes children more quickly (all within one minute), while the other signal was found to take two minutes or more for some children. At this stage, we are hopeful that a voice alarm will be more effective in waking more people (children and vulnerable adults) who are at risk of sleeping through an alarm.
Conclusion
We hope this article has led you to the same conclusion that we have reached—namely, that the notion we can rely on smoke alarms to awaken sleepers is largely a myth. Sure, traditional smoke alarms are much better than having no alarm at all and they will wake most adults under “ideal” circumstances. Unfortunately, we can’t count on residential fires occurring under ideal circumstances. Of the people who die annually in residential fires, only about 1 in 10 are sober, able-bodied and aged six to 65.
What We Learned About Alarms
Television stations across America have been partnering with local fire departments recently, conducting investigations to see if smoke detectors will awaken sleeping children. The results were similar - that many children will not wake up to the sounds of an activated smoke detector.
On July 31, 2003, Underwriters Laboratories Standards Technical Panel released its recommendations for improving the effectiveness of smoke detectors in awakening children. Their conclusions and recommendations are as follows:
- The majority of children between the ages of birth and five years are developmentally incapable of responding appropriately during fire/smoke emergencies. Caretaker rescue is the only reliable method to decrease morbidity and mortality in this age group.
- Children five to 16 years of age are unlikely to awaken fully to auditory stimuli currently produced by commercially available smoke detectors.
- There are no standardized scientific data regarding arousal and/or awakening to other types of nonbiological stimuli in this age group.
- Therefore, pending further research, rescue is the only currently known reliable method to decrease morbidity and mortality in sleeping children when faced with a fire/smoke emergency.
In other words, firefighters are going to have to get these children out! Children still need to be taught the basics of fire safety, but skills also need to be taught to their parents.
Current fire prevention efforts are geared toward conditioned responses, and skills that have become routine with practice. For many years, the conditioned response taught most has probably been “Stop, Drop and Roll.” It doesn’t matter how old a person is, when a firefighter asks them what they should do if their clothes should catch fire, the answer always comes back the same: “You stop, drop and roll!” So why do children and adults alike always remember this skill? It’s very simple; they hear it again and again and occasionally even act it out. “Stop, Drop and Roll” has become a conditioned response to our question. Our efforts now need to focus on families getting into a consistent routine of exiting their home every time a smoke detector activates. Research has proved that if you do something a minimum of 20 times, it becomes routine, or conditioned. Our smoke detector investigation showed that this statement is true.
Results and Recommendations
Parents need to determine what their child’s conditioned responses are in the home and make them a part of their family’s escape plans. In addition, families must routinely practice their escape plans and fire drills. Children and parents will need to determine vocal communication to wake everyone in the home should the smoke detectors activate.
Source: National Fire & Rescue Magazine - www.nfrmag.com
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