Heat exhaustion occurs when your heart and vascular system do not respond properly to high temperatures.

The symptoms of heat exhaustion resemble shock and include faintness, rapid heartbeat, low blood pressure, an ashen appearance, cold clammy skin, and nausea. If you suspect heat exhaustion, get the person out of the sun and into a cool spot. Lay the person down and elevate his or her feet slightly. Loosen or remove most or all of the person's clothing. Give the person cold (not iced) water to drink, with a teaspoon of salt added per quart.

The main indication of heat stroke is a fever of 105 degrees Fahrenheit with hot, dry skin. Other signs include rapid heartbeat, rapid and shallow breathing, either elevated or lowered blood pressure, and confusion or unconsciousness. If you suspect heat stroke, get the person out of the sun and into a cool spot. Cool the person by covering him or her with damp sheets or spraying with water. Direct air onto the person with a fan or a newspaper, and monitor the person's temperature with a thermometer. Stop cooling the person when his or her temperature returns to normal. If breathing ceases, start mouth-to-mouth resuscitation. Heat stroke is an emergency that needs immediate medical attention.