July 19, 2002
Lazy, Hazy Days of Summer Bring Increased Risks
of Heat Stroke and Heat Exhaustion
BLACKSBURG -- Acclimation is one of the best tools our bodies have for coping with heat stress. Unfortunately, many people don't give their bodies a chance to adjust to the hot, humid summer weather. They live, work, shop, and drive in air conditioning, putting them at greater risk for heat-related illness when they do work or play outside in the heat.
"By mid-July most of those who work outside have adjusted to the heat," says Bobby Grisso, Virginia Cooperative Extension specialist at Virginia Tech. "The body is efficient at maintaining a normal body temperature through evaporation of sweat. On really hot days, with maximum exertion, a person can sweat up to two quarts an hour."
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Humidity is what really makes the body feel uncomfortable in the heat. As the relative humidity increases, it feels warmer than the actual air temperature because the body can't sweat and naturally cool itself. This can lead to a person developing a heat-related illness on any hot, humid day.
"When your body temperature rises, your body tries to compensate. Your heart starts beating faster, you breathe faster, and your blood vessels dilate to bring more blood closer to the surface to cool," explains Grisso. "These physical changes can increase the risk of complications from other illnesses such as coronary artery disease, congestive heart failure, emphysema or asthma, and it can make it harder to control diabetes."
Individuals taking medicines that inhibit sweating can be at higher risk for heat illnesses or heat stroke. Anyone taking antihistamines, drugs prescribed for some psychological illnesses, blood pressure medicines, or any stimulants or drugs that increase the metabolism needs to be very careful. "When in doubt," says Grisso, "ask your pharmacist if any medications you're taking can affect your ability to sweat or be in the heat for an extended time."
Grisso suggests, "Drinking plain, old-fashioned water works well to replace fluids if you've been outside for several hours. But if you've been sweating profusely for more than a few hours, you'll need to replace electrolytes too. Eat a banana, drink fruit juices, or drink a sports drink that provides electrolytes. You may need to replace up to two quarts of fluid for every hour spent in strenuous exercise. Avoid drinking alcohol or caffeinated beverages."
Heat-related illnesses range from fatigue and cramps to heat exhaustion and heat stroke.
"While you can't control the heat and humidity, you can control your activity level. When you begin to notice the first signs of heat illness, reduce or stop activity, get in the shade, remove excess clothing, apply cool cloths to help lower body temperature, drink fluids, and take it easy.
"Children may not pay attention so it is up to the adults to watch for warning signs," says Grisso. "Have them take a break and cool down when they need it. The first signs of heat exhaustion for children are when they become flushed, crabby, and don't feel well."
Summer is only half over. There are still plenty of hot, humid days ahead. Being aware of the risks and signs of heat related illness can help keep everyone safer.
Contact: Bobby Grisso
Virginia Cooperative Extension engineer
Virginia Tech
(540) 231-6538
rgrisso@vt.edu
Writer: Nancy Templeman
Agriculture and Extension Communications
Virginia Tech
(540) 231-6185
templemn@vt.edu
Visit Virginia Cooperative Extension
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