The temperature is forecast to break 100 degrees this week, with high humidity and little chance for rain. People working outside, infants and children, the elderly and people with chronic medical conditions can be particularly vulnerable to heat-related illness. That's why Knox County Health Department (KCHD) urges the public to use caution and know the signs of and treatment for heat stroke.

"The body normally cools itself through perspiration. You perspire and the sweat evaporates on your skin, it has a cooling effect," said Dr. Martha Buchanan, KCHD director. "But during physical activity in extreme heat, your natural sweating mechanism may be overwhelmed, causing your body temperature to rise to 106 degrees or higher within 10 to 15 minutes.

"High humidity levels increase your risk because the sweat you produce isn't evaporated as quickly. It's important to know the signs of heat exhaustion and heat stroke so you can stop your body from overheating."

The following symptoms are warning signs of heat exhaustion: Heavy sweating Paleness Muscle cramps Weakness Dizziness Headache Nausea or vomiting Fainting

Treatment for heat exhaustion includes moving to a cooler place, resting and drinking plenty of water. While heat exhaustion is not life threatening, heat stroke kills about 50 percent of those who experience it. One key sign that someone has heat stroke is lack of perspiration.

"Someone with classic heat stroke will have red, hot, dry skin," Buchanan said. "The pulse will be rapid, and body temperature will rise to above 103 degrees. In addition to the signs of dizziness and nausea, which you see in heat exhaustion, the person also may develop a throbbing headache, become confused or even become unconscious."

If you suspect someone is experiencing heat stroke, call 911 immediately and do the following:

Move the person to a cool place. Place the victim's feet higher than his/her head. Cool the person as quickly as possible any way you can, such as removing clothing, soaking the person with cold water and fanning him/her. Monitor the victim's body temperature and continue cooling efforts until the body temperature drops below 103 degrees.

According to the Centers for Disease Control and Prevention, more people in the United States have died from exposure to heat than by hurricanes, lightning, tornadoes, floods and earthquakes combined.

KCHD offers these tips for preventing heat exhaustion and heat stroke:

Stay informed about the weather forecast in your area. Drink plenty of cool, nonalcoholic beverages before you start any outdoor activity. Thirst is a sign the body is dehydrated. Increase your fluid intake regardless of your activity level. Wear a hat and sun screen. Clothing should be light-colored, lightweight and loose-fitting. Cotton allows the skin to breathe better than most synthetics. New, high-tech wicking fabrics, found in most fitness clothing, also are good helping the body cool itself through evaporation. Air-conditioning is the number one protective factor against heat-related illness and death.
       - If you home isn't air-conditioned, go to the mall, library or other public area, or
       - Use a fan to circulate air or sit in a bathtub of cool water and.
       - Drink plenty of water and avoid soft drinks and alcoholic beverages.
Stay inside during the hottest times of day and exercise or do yard work when the temperature decreases. Pace yourself if you are not accustomed to the heat. Avoid using heavy body lotions, hair gels or sprays, which can inhibit the body's cooling ability. Monitor children and the elderly, who are the most susceptible to heat-related illness. At-risk adults should be checked twice a day. Do not leave infants, children or pets in a parked car, even for a few minutes. Provide plenty of cool, fresh water for your pets and keep them inside or provide access to shade.