EXTREME HEAT
A Prevention Guide to Promote Your Personal Health and Safety
Centers for Disease Control and Prevention
(CDC)
U.S. Department of Health and Human Services
Public Health Service
1996
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Contents
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Summer heat waves bring unusually high temperatures that may
last for days or weeks. In the summer of 1980, a severe heat wave
hit the United States, and nearly 1,700 people lost their lives from heat-related
illness. Each year, high temperatures put people at risk.
People suffer heat-related illness when the body's temperature
control system is overloaded. The body normally cools itself by
sweating. But under some conditions, sweating just isn't enough.
In such cases, a person's body temperature rises rapidly. Very
high body temperatures may damage the brain or other vital organs.
Several factors affect the body's ability to cool itself
during extremely hot weather. When the humidity is high, sweat
will not evaporate as quickly, preventing the body from releasing
heat quickly. Other conditions that can limit the ability to regulate temperature
include old age, obesity, fever, dehydration, heart disease, poor
circulation, sunburn, and drug and alcohol use.
Summertime activity, whether on the playing field or the
construction site, must be balanced with measures that aid the
body's cooling mechanisms and prevent heat-related illness. This pamphlet tells how
you can prevent, recognize, and cope with heat-related health
problems.
To protect your health when temperatures are extremely high,
remember to keep cool and use common sense. The following tips
are important.
Drink Plenty of Fluid
Increase your fluid intake - regardless of your activity
level. During heavy exercise in a hot environment, drink 2-4
glasses (16-32 ounces) of cool fluids each hour.
Caution: If your doctor has prescribed a
fluid-restricted diet or diuretics for you, ask your doctor how much
you should drink.
During hot weather, you will need to drink more liquid than
your thirst indicates. This is especially true for persons 65
years of age and older who often have a decreased ability to respond
to external temperature changes. Drinking plenty of liquids during
exercise is especially important. However, avoid very cold
beverages because they can cause stomach cramps. In addition,
avoid drinks containing alcohol because they will actually cause
you to lose more fluid.
Replace Salt and Minerals
Heavy sweating removes salt and minerals from the body. These
are necessary for your body and must be replaced. The easiest and
safest way to replace salt and minerals is through your diet.
Drink fruit juice or a sports beverage during exercise or any
work in the heat. Do not take salt tablets unless directed by
your doctor. If you are on a low-salt diet, ask your doctor before
changing what you eat or drink-especially before drinking a
sports beverage.
Wear Appropriate Clothing and Sunscreen
Wear as little clothing as possible when you are at home.
Choose lightweight, light-colored, loose-fitting clothing. In the
hot sun, a wide-brimmed hat will provide shade and keep the head
cool.
Sunburn affects your body's ability to cool itself and causes
a loss of body fluids. It also causes pain and damages the skin.
A variety of sunscreens are available to reduce the risk of
sunburn. The protection that they offer against sunburn varies. Check
the sun protection factor (SPF) number on the label of the
sunscreen container. Select SPF 15 or higher to protect yourself
adequately. Apply sunscreen 30 minutes before going outdoors and
reapply according to package directions.
Pace Yourself
If you are unaccustomed to working or exercising in a hot
environment, start slowly and pick up the pace gradually. If exertion
in the heat makes your heart pound and leaves you gasping for
breath, STOP all activity, get into a cool area, or at least in
the shade, and rest, especially if you become lightheaded,
confused, weak, or faint.
Stay Cool Indoors
The most efficient way to beat the heat is to stay in an
air-conditioned area. If you do not have an air conditioner or evaporative
cooling unit, consider a visit to a shopping mall or public
library for a few hours. Contact your local health department to
see if there are any heat-relief shelters in your area. Electric
fans may be useful to increase comfort and to draw cool air into
your home at night, but do not rely on a fan as your primary
cooling device during a heat wave. When the temperature is in the
high 90s or higher, a fan will not prevent heat-related illness.
A cool shower or bath is more effective way to cool off. Also,
use your stove and oven less to maintain a cooler temperature in
your home
Schedule Outdoor Activities Carefully
If you must be out in the heat, try to plan your activities so
that you are outdoors either before noon or in the evening. While outdoors,
rest frequently in a shady area. Resting periodically will give
your body's thermostat a chance to recover.
Use a Buddy System
When working in the heat, monitor the condition of your
coworkers and have someone do the same for you. Heat-induced illness
can cause a person to become confused or lose consciousness. If
you are 65 years of age or older, have a friend or relative call
to check on you twice a day during a heat wave. If you know
anyone in this age group, check on them at least twice a day.
Monitor Those at High Risk
Those at greatest risk of heat-related illness include:
- infants and children up to four years of age
- people 65 years of age or older
- people who are overweight
- people who overexert during work or exercise
- people who are ill or on certain medications
Infants and children up to four years of age are sensitive to
the effects of high temperatures and rely on others to regulate
their environments and provide adequate liquids. People 65 years
of age or older may not compensate for heat stress efficiently, and
are less likely to sense and respond to changes in temperature.
Overweight people may be prone to heat sickness because of their
tendency to retain more body heat. Any health condition that causes
dehydration makes the body more susceptible to heat sickness. If
you or someone you know is at higher risk, it is important to
drink plenty of fluids; avoid overexertion; and get your doctor
or pharmacist's advice about medications taken for high blood pressure, depression, nervousness,
mental illness, insomnia, or poor circulation.
Adjust to the Environment
Be aware that any sudden change in temperature, such as an
early summer heat wave, will be stressful to your body. You will have
a greater tolerance for the heat if you limit your physical
activity until you become accustomed to the heat. If traveling to a
hotter climate, allow several days to become acclimated before
attempting any vigorous exercise, and work up to it gradually.
Use Common Sense
Avoid hot foods and heavy meals-they add heat to your body. Do
not leave infants, children, or pets in a parked car. Dress infants
and young children in cool, loose clothing and shade their heads
and faces with hats or an umbrella. Limit sun exposure during the
mid-day hours and in places of potential severe exposure such as
beaches. Ensure that infants and children drink adequate amounts
of liquids. Give your pet plenty of fresh water, and leave the
water in a shady area.
Even short periods of high temperatures can cause serious
health problems. Two common problems are heat stroke and heat exhaustion.
Heat Stroke
Heat stroke occurs when the body becomes unable to control its
temperature: the body's temperature rises rapidly, the sweating
mechanism fails, and the body is unable to cool down. Body
temperature may rise to 106F or higher. within 10-15 minutes.
Heat stroke can cause death or permanent disability if emergency
treatment is not given.
Recognizing Heat Stroke
Warning signs of heat stroke vary but may include:
- an extremely high body temperature (above 103F, orally)
- red, hot, and dry skin (no sweating)
- rapid, strong pulse
- throbbing headache
- dizziness
- nausea
- confusion
- unconsciousness
What to Do
If you see any of these signs, you may be dealing with a life
threatening emergency. Have someone call for immediate medical assistance
while you begin cooling the victim:
- Get the victim to a shady area.
- Cool the victim rapidly using whatever methods you can
For example, immerse the victim in a tub of cool water; place
in a cool shower; spray with cool water from a garden hose; sponge with
cool water; or if the humidity is low, wrap the victim in
a cool, wet sheet and fan him or her vigorously.
- Monitor body temperature, and continue cooling efforts
until the body temperature drops to 101-102F.
- If emergency medical personnel are delayed, call the
hospital emergency room for further instructions.
- Do not give the victim alcohol to drink.
- Get medical assistance as soon as possible.
Sometimes a victim's muscles will begin to twitch
uncontrollably as a result of heat stroke. If this happens, keep
the victim from injuring himself, but do not place any object in
the mouth and do not give fluids. If there is vomiting, make sure
the airway remains open by turning the victim on his or her side.
Heat Exhaustion
Heat exhaustion is the body's response to an excessive loss of
water and salt contained in sweat. Those most prone to heat exhaustion
are elderly people, people with high blood preset and people working
or exercising in a hot environment.
Recognizing Heat Exhaustion
Warning signs of heat exhaustion include:
- heavy sweating
- paleness
- muscle cramps
- tiredness
- weakness
- dizziness
- headache
- nausea or vomiting
- fainting
The skin may be cool and moist. The victim's pulse rate will
be fast and weak, and breathing will be fast and shallow. If heat exhaustion
is untreated, it may progress to heat stroke. Seek medical
attention immediately if:
- symptoms are severe, or
- the victim has heart problems or high blood pressure.
Otherwise, help the victim to cool off, and seek medical
attention if symptoms worsen or last longer than 1 hour.
What to Do
Cooling measures that may be effective include:
- cool, non-alcoholic beverages, as directed by your
physician
- rest
- cool shower, bath, or sponge bath
- an air-conditioned environment
- Lightweight clothing
Heat Cramps
Heat cramps usually affect people who sweat a lot during
strenuous activity. This sweating depletes the body's salt and moisture.
The low salt level in the muscles causes painful cramps. Heat
cramps may also be a symptom of heat exhaustion.
Recognizing Heat Cramps
Heat cramps are muscle pains or spasms - usually in the
abdomen, arms, or legs - that may occur in association with strenuous
activity. If you have heart problems or are on a low sodium diet,
get medical attention for heat cramps.
What to Do
If medical attention is not necessary, take these steps:
- Stop all activity, and sit quietly in a cool place.
- Drink clear juice or a sports beverage.
- Do not return to strenuous activity for a few hours after
the cramps subside because further exertion may lead to
heat exhaustion or heat stroke.
- Seek medical attention for heat cramps if they do not
subside in 1 hour.
Sunburn
Sunburn should be avoided because it is damaging to the skin.
Although the discomfort is usually minor and healing often occurs
in about a week, a more severe sunburn may require medical
attention.
Recognizing Sunburn
Symptoms of sunburn are well known: skin becomes red, painful,
and abnormally warm after sun exposure.
What to Do
Consult a doctor if the sunburn affects an infant under 1 year
of age or if these symptoms are present:
- fever
- fluid-filled blisters
- severe pain
Also, remember these tips when treating sunburn:
- Avoid repeated sun exposure.
- Apply cold compresses or immerse the sunburned area in
cool water.
- Apply moisturizing lotion to affected areas. Do not use
salve, butter, or ointment.
- Do not break blisters.
Heat Rash
Heat rash is a skin irritation caused by excessive sweating
during hot, humid weather. It can occur at any age but is most common
in young children.
Recognizing Heat Rash
Heat rash looks like a red cluster of pimples or small
blisters. It is more likely to occur on the neck and upper chest,
in the groin, under the breasts, and in elbow creases.
What to Do
The best treatment for heat rash is to provide a cooler, less
humid environment. Keep the affected area dry. Dusting powder may
be used to increase comfort, but avoid using ointments or
creams-they keep the skin warm and moist and may make the condition
worse.
Treating heat rash is simple and usually does not require
medical assistance. Other heat-related problems can be much more severe.
These self-help measures are not a substitute for medical care
but may help you recognize and respond promptly to warning signs
of trouble. Your best defense against heat-related illness is prevention. Staying
cool and making simple changes in your fluid intake, activities, and
clothing during hot weather can help you remain safe and healthy.
Introduction | During Hot Weather | Hot Weather Health
Emergencies | Other Heat-Related Health Problems
| One last hot tip...
CDC Prevention
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See also the Spanish
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