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Heat Injuries |
OVERVIEW
Heat injuries can occur anywhere, depending on physical activity (work rate) and clothing
worn. However, they occur most frequently during warm-weather training, exposure to
high climatic temperatures, high humidity, and bright sunlight. These conditions make it
difficult for the body to regulate its temperature. Hot weather
also increases daily water requirements, because body water is
lost as sweat. Dehydration leads to added heat stress, increased
susceptibility to heat injury, reduced work performance, and
degraded mission capability.
ACCLIMATIZATION
When the mission permits, all personnel should work and exercise in a
manner so that they gradually become acclimatized to the heat and
humidity in the AO. Significant heat acclimatization requires at least
3 to 5 days and full acclimatization can take up to 2 weeks. Exercising in the heat and
humidity for 1 to 2 hours daily, gradually increasing the workload each day, can produce
acclimatization. (Refer to Table 3-1 in Chapter 3.) When the mission does not permit time
for gradual increases in workload, then leaders and buddies must observe each other and
ensure that everyone drinks plenty of water during each work period. Individuals leaving
a cold or cool climate will require additional time to become acclimatized to a hot climate.
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DRINK PLENTY OF WATER
Depending on the heat and activity level, you may need to drink from
1 /2 to 1 1 /4 quarts of
water per hour—3 gallons/12 liters per day in hot, dry climates. Drinking water is a must
in order to prevent heat injury. If desired, individuals may add flavoring to the water to
enhance consumption. Field rations/meal(s), ready to eat (MRE) have flavoring for water in
each meal. It the flavoring is used, add it to water in your canteen cup. Do not add flavoring
to the water in your canteen; it increases the risk of contamination and illness. Never flavor
the bulk source water supply. (Flavoring the bulk source water supply will reduce the action
of water disinfectants.) See Table 3-1 for water intake requirements.
- Drink extra water before starting any mission or hard work. Cool water (60° to
70° Fahrenheit [F]) is absorbed faster than cold water.
- Drink small quantities of cool fluids frequently. Carbohydrate/electrolyte beverages
(sport drinks) may provide supplemental nutrients under conditions of extreme
calorie and water requirements; such as extremely vigorous activity. However,
they cannot replace and must not be used to meet all water requirements.
- Drink “non-caffeinated” fluids even if you are not thirsty. (Caffeine increases
water requirements in all environments.)
- Refill your canteens at every opportunity, using only treated water, if possible.
NOTE
The color and volume of the urine steam are good indicators of a service
member’s hydration status. If your urine stream is dark yellow and the
volume is small, or if you are constipated and experience hard stools, you
may not be drinking enough water. Maintain a urine stream that is clear
or light yellow. Thirst is not a good indicator of dehydration during
physical activity.
USE WORK/REST CYCLES
- Work and rest as your leader directs. (See Table 3-1.) A rest period helps prevent
dangerous increases in body temperatures by minimizing heat production.
- Work and rest in the shade, if possible.
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EAT ALL MEALS TO REPLACE SALTS
Eating all meals in the field will usually provide the body’s requirements for
salts. Field rations/MRE meet the daily requirements for minerals and
electrolytes (sodium). DO NOT take extra salt in meals unless medically
indicated.
NOTE
DO NOT TAKE SALT TABLETS. One salt tablet
increases your water requirement by at least a pint. Salt
draws water from muscles to dilute your blood. Salt tablets
can cause vomiting.
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RECOGNIZE THE RISK OF MISSION-ORIENTED PROTECTIVE
POSTURE/BODY ARMOR/ARMORED VEHICLES
- Mission-oriented protective posture (MOPP)/body armor increases
your heat stress. (See Table 3-1.) You must—
- Drink more water. DO NOT EXCEED 1 1 /4 QUARTS PER HOUR.
- Work and rest as your leader directs.
- You may be at a greater risk of heat injuries when in armored vehicles—you may
need to drink more water.
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MODIFY YOUR UNIFORM
When directed/authorized by your commander to reduce heat stress and to protect against
ultraviolet (UV) radiation, you should—
- Unblouse pants from boots.
- Cover all skin exposed to sun; wear sunscreen and lip balm with a
sun protection factor of 15 or higher.
- Protect the eyes from UV with UV-protective sunglasses,
especially wraparound sunglasses.
- Seek shade when resting outdoors.
- Keep clothing loose at the neck, wrists, and lower legs.
NOTE
When the threat from biting arthropods is high, keep your shirtsleeves
rolled down and pants bloused in boots.
NOTE
See Graphic Training Aid (GTA) 8-5-50 and FM 21-11, for information
on heat injury prevention and first aid.
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Index
Index
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