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Heat Stroke
What
causes heat stroke?
Summer temperatures in the United States can climb above 100 degrees Fahrenheit (38 degrees Celsius), making heat stroke a big problem.
Heat stroke can be fatal in
many cases because it happens so quickly -- there is not much time to react.
Let's say that it really is
100 degrees F outside. The human body wants to stay at 98.6 degrees F.
The only way to stay at 98.6
is to sweat. By
putting moisture on the skin and letting it evaporate, your body can cool
itself very effectively and keep its temperature in the proper range.
Sweat works really well as
long as there is plenty of water in
your body -- it takes water to manufacture sweat.
If you run out of water,
sweat stops and your body rapidly overheats.
It turns out that it is
extremely easy to run out of water -- your body can produce 0.5 gallons (2
liters) of sweat every hour in a hot environment.
Unless you are drinking water
at the same rate, you will dehydrate and
then stop sweating.
Your internal thirst meter
often is not sensitive enough when you need that much water (and it has been
said that by the time you feel thirsty, you're already dehydrated), so you have
to keep drinking regardless of how thirsty you feel.
The other thing that can lead
to heat stroke is very high humidity, which keeps sweat from
evaporating.
In either case -- be it the
lack of sweat or the inability to evaporate it -- the core body temperature can
rise very quickly if it is hot outside.
Once the core gets to 106 degrees F, it is a serious problem.
Symptoms include red, hot,
dry skin (the body dilates skin blood vessels to
try to release heat, making the skin red, and the dryness comes from lack of
sweat), rapid heart rate,
dizziness and confusion.
The dizziness and confusion
come from the high body temperature, which affects the brain.
For children and pets, one way for heat stroke to happen
suddenly and unexpectedly involves a hot car or a hot room in a house.
Cars are especially
dangerous. At HowStuffWorks we did the following
experiment:
1.
We turned on the air conditioner in a car at 3:30 p.m. on
a sunny, hot summer afternoon in Raleigh, NC.
2.
We waited until the
interior of the car cooled to a comfortable 75 degrees F.
3.
We turned the engine off.
Within 15 minutes, the
interior temperature of the car was 110
degrees F. This temperature is quickly fatal.
The reason the temperature
rises so high and so fast is because the interior of a car is an excellent
solar oven that uses the greenhouse
effect to trap heat.
Sunlight heats the sheet
metal of the car, and it streams in through the windows to heat the interior.
It turns out that glass is
completely transparent to visible light but opaque to infrared
light -- and infrared light is the heat that is trying to radiate back out of
the interior.
So the temperature rises
rapidly, to the point where you often cannot touch the steering wheel without getting singed.
Leaving the window cracked is
not going to help -- it is never safe to leave a child or pet in a parked car
for any length of time.
The only solution for heat
stroke is to cool the person down.
You can:
·
Try to get the person to drink water if the person is conscious.
·
Soak the person's entire body
in cool water.
·
Sponge cool water onto the
person's body.
·
Apply ice packs to the head, neck, armpits
and groin.
If not treated, heat stroke
can be fatal in less than an hour.
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