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Summer 2007 Issue
    Cover Article
    Message from the Director
    Field Notes: Leave Only Footprints, Take Only Pictures
    Mission at High Altitude: KCS & NOLS Team to Train Sherpas
    A Wilderness Twist to Traditional Medical School
    Wild Side of Medicine: Heat Illness in the Backcountry
    NOLS Environmental Sustainability Initiative Update
    NOLS River Courses
    Alumni Profile: Nico Marceca
    Recipe Box: Creative Menu Planning for Short Trips
    Gear Room: Personal Locator Beacons
    Book Review: Give Me Mountains for my Horses
Movie Review: Everything's Cool
Matching Gifts Stretch Your Scholarships Giving
Passing it Forward: NOLS Donors Support Student Experiences
Issue Room: Land Development Looms Around NOLS Mexico
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Mercury Rising: Heat Illness in the Backcountry

By Tod Schimelpfenig, WMI Curriculum Director

Prevention of heat illness is a key leadership task in the heat and humidity of summer.
Photo: Alexis Alloway

The North American summer is upon us. People are heading outdoors to climb, hike, fish, bike and run. Summer’s sun and higher temperatures mean we’re all exposed to potential heat-related illnesses, ranging from something as simple as fainting, to heat exhaustion or even life-threatening heat stroke.

Prevention of heat illness is a leadership task before it becomes a medical problem. Be alert in yourself and those around you for these signs of developing heat illness: fatigue, headache, weakness, irritability and malaise. Don’t underestimate the stress of heat, humidity, intense sun, wind and dehydration.

High heat and humidity are obvious risk factors. Air temperatures exceeding 90ºF (32ºC) and humidity levels above 70 percent impair the body’s ability to lose heat through radiation and evaporation. Add lack of acclimatization, dehydration, exertion and intense sun to this mix and all the caution flags should be raised.

Additional heat illness risk factors are age, poor general health, medications and fatigue. The very young and the elderly are less efficient at heat loss, as are people who are very muscular or overweight. Antihistamines, antipsychotic agents, thyroid hormone medications, amphetamines and alcohol have been implicated in the development of heat illness. Some of these medications interfere with thermoregulation; others increase metabolic activity or interfere with sweating.

Heat illness can happen within hours in extreme conditions, but it can also be cumulative. Be alert to several days of stress: hard hiking, tired people, hot weather, warm nights and less than optimal fluid intake.

Being in the outdoors is a thinking person’s game: know heat illnesses’ risk factors, watch your group and their behaviors, and take action. From the links to the courts and from the playing fields to the backcountry, heat illness prevention is a leadership challenge for everyone in the summer.

Prevention Tips for Heat Illness

  • Stay hydrated. Thirst can be an unreliable and delayed stimulus to drink. Drink enough to urinate clear to light yellow urine regularly. Snack regularly or use an electrolyte-containing beverage to avoid hyponatremia (too-low sodium levels in the blood).
  • Exercise cautiously during high heat and humidity.
  • Know the warning signs of impending heat illness: dark-colored urine, dizziness, headache and fatigue.
  • Exercise early or late in the day in hot environments.  Rest often. Hot weather is a good reason for a mid-day siesta. Move to the rhythms of nature, not a self-imposed schedule.
  • Plan 10 days to two weeks to acclimate. We can adjust to working in the heat if we give ourselves the time to acclimatize.
  • Wear well-ventilated, open weave clothing. Cover your head and wear sunglasses.
  • Break the heat stress when you can. Rest in cool, shady places.

Treatment Principles for Heat Illness

  • Provide a cool environment, get people out of the heat, and loosen clothing.
  • Spray the patient with water and fan the body to enhance evaporation.
  • Hydrate with water, a dilute solution of sugar water with a teaspoon of salt, or a sports drink.
  • Rest until symptoms subside.

For more information:

See the WMI of NOLS Curriculum Update for more information. Want to know even more? Check out Hot Day and Hot Heads: Understanding Heat Illness by WMI Instructor Buck Tilton

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