Understanding the dynamics of residential fires can make you and your family safer. In the last 10 years, while there have been deaths caused by fire, these have never been in commercial premises where fires and their consequences are generally better understood and protected against.
The occurrence of residential fires arises from:
- the many causes of potential fires; and
- the inadequacy of fire alarm systems and their failure to allow for the facts of human biology.
Most victims die as a result of breathing in smoke and poisonous compounds, long before a fire becomes hot enough to burn them.
- Causes of fire and their prevention
- How a typical fire causes death
- What you can do to improve detection
- Human factors which need to be understood
- Scientific studies
- Standards Australia Guidelines for Safe Housing Design AS 4226-2008
The best defence against fires is installing a smoke alarm. Since the early 1970s, when smoke alarms made their way into homes, residential fire deaths have been cut in half with the statistics showing that homes with smoke alarms - operational or not - have a death rate 40 to 50 percent lower than the rate for homes without alarms.
Today, the overwhelming majority of fatalities take place in homes that aren't equipped with alarms or in homes where the equipment is broken, dismantled, or missing a battery. Half of the people killed in home fires each year die in the 6 percent of homes that don't have smoke alarms. Of the fatalities that do take place in homes equipped with alarms, half occur in cases in which the smoke alarm doesn't sound.
In modern houses most fires are caused by electricity. Three of the most common causes are:
- poorly cleaned appliances such as TVs, computers and videos igniting a build-up in dust when if they are left on standby over night;
- fridge motors burning out after an electrical storm; and
- night lamps left near curtains.
Risk can be reduced by turning-off appliances and not leaving them in standby mode, as well as cleaning them as frequently as possible.
You should also install circuit breakers on the electrical circuits to protect against overload. Please note that the old fuse type of protection could allow cables and connections to catch fire, so these should be replaced.
Typically residents die from smoke inhalation, not direct exposure to fire.
In a typical fire, say one started by an electrical fault, the original outbreak may smoulder for an hour or even more. During this period it will produce a lot of toxic smoke and it is during this smouldering stage the smoke will first rise to the ceiling and gradually drop down until it is the air that you are breathing and you will not wake up..
The smoke given off by today's furniture and room fittings contain high levels of toxic gases.
Once the heat has built up to cause ignition a typical Queensland home can burn down in less than 10 minutes.
The base level of security can be provided by having your electrician install 240-volt optical smoke alarms with a relay output that allows connection to a security system. Install a security system that has an external siren that can be mounted under the eaves of your house next to your main bedroom window.
You can enhance this level of security by having our alarm monitored by a security company who will respond with a patrol within 10 minutes.
In a 2002 Brisbane incident a family of 4 died in a house fire. They’d had an evening meal and retired to bed around 9:00 p.m. The parents had drunk two glasses of wine with the meal.
The fire, which was started by an electrical fault, smouldered for two hours, eventually setting off a hallway smoke alarm.
None of the family heard the alarm.
In studies only 5.6 per cent of children between one and fifteen have been found to be able to hear an alarm whilst asleep.
An adult who has drunk two glasses of wine will need an alarm with a noise level at 98 decibels (slightly higher than the sound produced by your average motor mower).
Finally at midnight neighbours notice the smoke and call the fire brigade, but it was too late. While the house hadn’t burst into flames, the noxious fumes of smouldering furniture and fittings had been enough to kill all the inhabitants.
A number of scientific studies explored the human ability to respond to fire alarms. We highlight two here.
Bruck, a psychologist at Victoria University in Australia, was the first to identify the problem. In her 1999 study published in the Fire Safety Journal, Bruck tested 20 children between the ages of 6 and 17 to determine their response to a 60-decibel alarm sounding at their pillows.
She conducted her test twice and found 17 of the children slept through one or both tests. Two of the three who woke were 16 and 17 years old, among the older children in the sample.
Indeed, for the children 15 and under, the reliable waking rate was only 5.6 percent. In contrast, Bruck found all of the parents woke when the alarms sounded.
In subsequent research, Bruck's findings further complicated the issue: simply installing an alarm in a child's room is unlikely to solve the problem. In a presentation to the fourth Asia-Oceania Symposium on Fire Science and Technology in 2000, Bruck and fellow researcher Angela Bliss reported their findings from a study of 28 children between the ages of 6 and 15.
In two tests, the children were exposed to an 89-decibel alarm; half slept through one or both tests. Among the 6 to 10 year olds, that percentage climbed to 71 percent. When children did wake, they were groggy for several minutes, a factor that might well have impaired their ability to make life-saving decisions in a true emergency.
While adults and fire protection experts may be surprised by those numbers, kids themselves might not be.
Derrick Ethridge, fire prevention officer for the Loyalist Township Emergency Services in Ontario, Canada, decided to study the issue of audibility when children in the schools he visits told him they didn't think they'd hear an alarm if it went off. "They kept telling me 'I don't think I'd hear it,' or 'I sleep with my door closed,' or 'I don't think I'd wake up,' " he recalls. "I suspected there was a problem just on the basis of what the kids were telling me, and I wanted to find out if that was true."
With the help of Professor Alistair MacLean of the Queens University Sleep Lab, the Canadian Hearing Society, the Limestone and Algonquin school boards, and the parents of 222 Loyalist Township sixth graders, Ethridge decided to conduct an experiment. Parents were asked to activate the smoke alarms outside their sleeping children's bedrooms between 9 and 11 p.m. on two separate nights in April 2002 and time how long it took the children to awaken. Tests were conducted once with the door closed and once with it open. The children knew they'd be tested but didn't know when.
The team found 31 percent of the children didn't wake up at all when the smoke alarm was activated, and 53 percent didn't react within the first minute. Ethridge later conducted random audibility tests of 22 of the homes. Testing once with the bedroom door open and again with it closed, he found audibility in some cases dipped as low as 64 decibels. "Some parents wrote back, 'I took the damn smoke alarm off the ceiling, put it over my kid's head and he didn't move.' Or they said the alarm rang until the batteries were dead, and the child never woke up," he says. "They were definitely concerned."
Australian Standards give some guidance on safe housing design. You can download an exceprt from the document by clicking here and you can obtain a copy from the SAI online store.