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When hard work is performed in a hot
environment, blood is sent to the skin to cool the body, primarily through
evaporation of sweat. As sweating continues, often at a rate of more than
1 liter per hour, the body loses lots of fluid. That can compromise heart
and circulatory function and the ability to work. If fluids are not replaced,
the temperature-regulating process begins to break down, work becomes
impossible, and the possibility of life-threatening heat stroke increases
dramatically.
Heat Disorders
Heat stress disorders include heat cramps, heat exhaustion, and heat stroke.
Heat cramps are involuntary muscle contractions caused by failure to replace fluids or electrolytes, such as sodium and potassium. Cramps can be relieved with stretching and by replacing fluids and electrolytes.
Heat exhaustion is characterized by weakness, extreme fatigue, nausea, headaches, and a wet, clammy skin. Heat exhaustion is caused by inadequate fluid intake. It should be treated by resting in a cool environment and replacing fluids and electrolytes.
Heat stroke is a medical emergency caused by failure of the body's heat controls. Sweating stops and the body temperature rises precipitously. Heat stroke is characterized by hot dry skin, a body temperature above 105.8 F (41 C) mental confusion, loss of consciousness, convulsions, or even coma. Send for medical help at once and begin rapid cooling with ice or cold water, fanning the victim to promote evaporation. Treat for shock if necessary. For rapid cooling, partially submerge the victim's body in cool water.
Prevention
You can prevent the serious consequences of heat disorders by improving your level of fitness and becoming acclimated to the heat.
Maintaining a high level of aerobic fitness is one of the best ways to protect yourself against heat stress. The fit worker has a well-developed circulatory system and increased blood volume. Both are important to regulate body temperature. Fit workers start to sweat sooner, so they work with a lower heart rate and body temperature. They adjust to the heat twice as fast as the unfit worker. They lose acclimatization more slowly and regain it quickly.
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