THE PHYSIOLOGY: To maintain our body core temperature at 98.6 degrees F., we must constantly shed temperature in order to avoid overheating. At rest we generate enough heat to raise our body temperature about 2 degrees F per hour; vigorous exercise can increase heat production tenfold. As with hypothermia, heat is lost to the environment through conduction, convection, radiation and evaporation. The skin is the largest radiating system: approximately 65% of daily heat loss. The skin is also largely responsible for evaporation (sweat); as liquid converts to gas. This is our most important cooling mechanism. On hot, very humid days, cooling becomes extremely inefficient because sweat can not evaporate. Conduction describes heat lost from a warmer object to a cooler object. On a very hot day, you may not be able to shed heat via conduction, and you might even gain heat. Likewise you may not lose heat by convection - heat lost directly into the air - even with a breeze, because the warm air surrounding your body is being constantly being replaced by warm air.

SEVERITY: Heat exhaustion and heatstroke are part of the same process, but of differing severity. The major underlying cause for both of these heat illnesses is dehydration. Heat exhaustion is illness caused by elevation of body temperature that does not result in permanent damage. Heat-stroke is life-threatening; death can occur in as little as thirty minutes. It is caused by the generation of body heat faster than it can be shed. The brain, which can function only within a very narrow temperature range, begins to fail.

SYMPTOMS: Heat exhaustion is characterized by headache, dizziness, nausea, rapid pulse, rapid breathing and exhaustion. Thirst is a common complaint. Sufferers are so sweaty they often feel cool, grow goose bumps. and complain of chills. They may demonstrate minor confusion or irrational behavior. The signs of heat stroke are extreme confusion (in some cases, unconsciousness), seizures, increased heart and respiratory rates, loss of coordination and hot, red, wet skin. The change in mental function may be sudden, including irritability, disorientation, combativeness, and hallucinations or incoherent speech.

TREATMENT: To treat heat exhaustion change the scout's environment from hot to cool. This may be accomplished by moving him to a shady spot, wet him down and fan him. Of greatest import is to orally rehydrate him with water, preferably with a pinch of salt and, perhaps, a couple of pinches of sugar. It will take about an hour to get a quart of fluid back into his circulation. Heat exhaustion is not physiologically damaging, but it should be treated aggressively before it progresses to heat stroke. For hear stroke rapid cooling is required to save the scout's life. The best method includes removal of clothing, covering with wet cotton clothing and vigorously fanning. Ice packs at the neck, groin and armpits increase heat loss. Easing the patient into cold water is less effective and often dangerous. Since heat stroke patients are dehydrated, rehydration is critical. Unfortunately, getting the scout to drink is typically impossible. The patient should be evacuated as soon as possible, the cooling process continued. Relapses of heat stroke are common among recovered patients.

PREVENTION: 1. Avoid dehydration. [See the discussion of dehydration on this web page]. 2. Wear clothing appropriate for the temperature. Dress in layers. Wear a loosely fitted broad-brimmed hat. 3. Cool yourself off. Find a place in the shade and sit for a while. Look for a place where there is a breeze, which will cool you by evaporation from your skin and clothing. 4. Douse your bandanna in some water and tie it around your neck or put it on your head under your cap. 5 . Likewise, douse your t-shirt in water and put it back on. 6. Be watchful of the young and the old; their bodies do not regulate body temperature efficiently. 7 Stay in shape. Obesity, lack of conditioning, insufficient rest, ingestion of alcohol and illicit drugs all contribute to an increased risk of heat illness. 8. Condition yourself for the environment. Gradual increased exposure to work in a hot environment will allow you to acclimatize.

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