Radiant Heat - the killer in a bushfire
Radiant heat can kill. You need to cover up - dress to
protect yourself - take refuge from direct heat.
Every summer, people try to survive bushfires by wearing light
summer dresses, shorts, singlets, even swimsuits. They usually
die without the flames even touching their exposed skin. They don't
understand the real risks of bushfire - heat stroke, dehydration
even asphyxiation.
Radiant heat cannot transmit through solid objects
If you put your hand near an open flame, an electric heater element
or electric light bulb, you can feel the radiant heat it generates.
Draw your hand away and the amount of heat on your skin decreases.
Put something between your skin and the heat source and again,
your skin immediately feels cooler. That's all you need to remember
about radiant heat from bushfires - distance and shielding protect
you from dangerous exposure.
The danger is real. Radiant heat from the flame front of a bushfire
scorches vegetation well in front of its path. It kills animals
caught in the open. People can also die if they do not seek protection.
Death is caused by heat stroke, when the body's cooling system
fails, leading to heat exhaustion and heart failure.
Shield yourself from Radiant
Heat
Bushfires usually occur on days of high temperature. You
and your family may be in shorts or swimsuits and bare feet
and sandals.
Remember, the deadly effects of radiant heat are increased
by the amount of skin exposed to it. So as soon as you know
there are bushfires in your area, cover up!
Firefighters wear protective gear to survive. So should
you. Some personal protective clothing is general purpose
and you may already have it.
Put on natural fibre long pants and light long-sleeved wool
jumpers or close weave cotton shirts or overalls. Wear good
solid footwear - preferably leather and a sturdy hat.
Organise a fire cupboard or box at the beginning of the
fire season and pack it with clothing for all members of
the family.
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Take cover inside your house
As the fire front passes, radiant heat levels become extreme.
Your clothing will not be sufficient to protect you for the five
to 20 minutes it may take for the fire to pass.
Radiant heat cannot penetrate through solid objects, but will
pass through glass. That means your best protection is a well-prepared
house.
As the fire front passes, stay inside with doors and windows shut
to protect against spark entry. Remember, if you flee from your
house, you lose its protection against radiant heat.
Other structures such as brick walls can offer protection. Taking
shelter in pools, dams and water tanks is not a safe option. The
air above the water will be dangerous to breathe, and may be deadly
when inhaled.
Reduce the risk of dehydration
 Dehydration
occurs when fluid output from the body is greater than fluid input.
It is dangerous because it creates a build up of salts and minerals
in the body tissues which put strain on the kidneys. When the kidneys
fail, death can quickly follow.
The high air temperature during a bushfire and the added stress
of wearing extra clothing to shield against radiant heat will contribute
to make you sweat heavily.
The fluids you lose must be replaced continuously or you risk dehydration.
Keep cool, drink water often.
Drink cool fluids at every opportunity - even if you don't feel
thirsty. Drink often to replace the fluids you sweat off. Alcohol
and fizzy drinks must be avoided as they aid dehydration.
Children and the elderly are especially vulnerable, so pay extra
attention to their needs. Keep them indoors where they do not need
to wear heavy protective clothing for long periods. Cool the skin
by sponging with cold water. Make sure they drink frequently.
If caught on the road
 Remember,
if your plan is to leave when a fire is burning in your area, do
so before the fire threatens and road travel becomes dangerous.
Late evacuation is a deadly option. Declaration of a Total Fire
Ban, or other high fire risk days, should be your trigger to put
your plan into action.
If you are driving and see smoke ahead, always u-turn to safety
if you have the option. Avoid being caught out on the road during
a fire as it is highly dangerous - a car will not offer safe protection
from the radiant heat. However, if you are caught in a fire do
not get out and run. Being in a car is still better than
being in the open.
- Pull over to the side of the road into a clear area – a
dirt track may be the best option
- Try not to park the car in a place where it is surrounded
by vegetation that will burn - avoid long dry grass and scrub
- Ensure all windows and doors are tightly closed and shut all
air vents
- Put the hazard lights and headlights on so other vehicles
can see you
- Cover exposed skin as much as possible with clothes made of
natural fibres – not synthetic clothing
- Get down as low as possible below window level and cover up
with a woollen blanket until the fire front passes. You will
feel a reduction in the heat and then it is time to get out of
the car and move to safety. If travelling in the country, always
carry a woollen blanket in your car for this purpose
- Remember to drink lots of water to stop yourself from dehydrating
Surviving in cars – recent research
Recent research about car passenger survivability, found that
there is no real difference between having the car engine on or
off or the air conditioning on or off, if the car is caught in
a bushfire situation.
While recognising there is differing public advice relating to
this matter, CFA endorses the CSIRO findings that:
- An operating air conditioning system in recirculation mode "does
not have a significant effect on the tenability of the vehicle
during the peak of the exposure".
- "Engine operation during the event did not result in a
significant change in cabin tenability during the test program".
In summary, CFA advises that there is no real difference in having
the air conditioning system in the recirculation mode or switched
off. Additionally, there is no real difference in having the engine
running or switched off. The most important advice in relation
to passenger safety is to avoid being caught out in a car during
a
bushfire. Road travel
during a bushfire is highly dangerous.
For more information on how to protect your self from the radiant
heat of a bushfire Download
the Radiant Heat Brochure (pdf 474k)
Reference: Sargeant, A.J, Leonard, J., Brown, S.K. and Blanchi,
R. (2007) Civilian Passenger Vehicle Burnover Experimentation.
Conference Paper, AFAC/ Bushfire CRC Conference, Hobart 2007.
Find out more about making a bushfire survival plan:
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