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Too Much Exposure to Hot Conditions Can Cause Heat Stress

LOS ANGELES AIR FORCE BASE -- Heat Stress occurs when humidity, air temperature, radiant heat and too little air movement combine with heavy work and clothing to raise the body temperature beyond safe limits. Sweat, as it evaporates, is the body's main line of defense against heat - as sweat evaporates, it cools the body. In high humidity, sweating becomes more intense but doesn't evaporate, so no heat is lost. When water lost through sweating is not replaced, the body's heat control breaks down and body temperature climbs dangerously, subjecting the body to heat stress.

Maintaining a high level of physical fitness is one of the best ways to protect yourself from heat stress. The physically fit person has a well-developed circulatory capacity, as well as increased blood volume - important in regulating body temperature.

The person acclimated to the heat runs less risk of heat stress. The body adjusts to work in the heat in four to eight days by: 

· Increasing sweat production
· Improving blood distribution
· Decreasing skin and body temperature
· Decreasing heart rate (beats per minute for the same job may drop from 180 to 150)

Acclimatization may be hastened by taking 250 milligrams of vitamin C daily. About 1 to 1-1/2 hours of work a day in the heat is enough to acclimatize to a specific combination of work and heat. It provides partial acclimatization to more severe conditions. Adjust to hot weather activity gradually. Set a sensible pace, take frequent breaks, replace fluids and don't expect full production the first few days. Acclimatization persists for several weeks, but a tough weekend (fatigue, alcohol) leads to some loss.

Here are some tips on recognizing and treating heat-stress disorders. 

Heat cramps: 

Cause - Failure to replace salt lost in sweating
Symptoms - Painful muscle cramps
Treatment - Drink lightly salted water or lemonade, tomato juice or "athletic" drinks; stretch cramped muscles

Heat exhaustion: 

Cause - Failure to replace water and salt lost in sweating
Symptoms - Weakness, unstable gait, or extreme fatigue; wet, clammy skin; headache, nausea, collapse
Treatment - Rest in the shade and drink lightly salted fluids


Cause - Failure to replace water losses over several days
Symptoms - Weight loss and excessive fatigue
Treatment - Drink fluids and rest until body weight and water losses are restored.

Heat stroke: 

Cause - Total collapse of temperature regulating mechanisms
Symptoms - Hot skin; high body temperature (106 degrees F or higher); mental confusion, delirium, loss of consciousness, convulsions
Treatment - Rapidly cool the victim immediately, either by immersing in cold water or soaking clothes in cold water and fanning vigorously to promote evaporative cooling. Continue until temperature drops below 102° degrees F. Treat for shock if necessary once temperature is lowered. Heat stroke is a medical emergency. Send for medical help and begin treatment at once. Brain damage and death result if treatment is delayed.