If it’s summer and you’re in Arkansas, you know it’s coming – a fry-an-egg-on-the-pavement heat wave. Even if it’s not an official heat wave, we have many more weeks of hot, humid, sticky weather before fall.

Heat can be a killer if you don’t take precautions. Heat waves kill more people in the United States than all other natural disasters combined. The Center for Climatic Research says an average of 1,500 people die annually because of the heat.

What’s a heat wave?

A heat wave is a prolonged period of excessively hot weather, usually with high humidity, when compared to the area’s normal seasonal weather and temperatures. It means at least five consecutive days with the temperature at least 9 degrees F. higher than average.

The heat index is what the temperature feels like to our bodies when the humidity is high. The heat index combines air temperature and relative humidity (moisture in the air).

When we get hot, our bodies cool down by sweating. As the sweat evaporates, the body’s temperature cools. However, on a humid day when the air is full of moisture, sweat cannot evaporate and the body stays hot. The opposite is true then humidity is low, or you’re in a dry climate. The body can cool itself quickly with just a small amount of sweating.

When is the heat index dangerous?

A heat advisory means a period of hot temperatures is expected and the heat index is likely to increase the risk of heat-related illness. The danger from heat is also higher when air pollution is high.

The Centers for Disease Control and Prevention says the usual progression of heat-related illness is:

  • Heat exhaustion causes heavy sweating, nausea or vomiting, fainting, a racing pulse and clammy skin. The person may also stagger, be confused or combative. Muscle cramps are often an early sign. To reverse it, stop activity, move to a cool location and apply wet, cool washcloths to the body. Heat exhaustion requires immediate medical treatment and rapid cooling. If you cannot reverse it, it quickly advances to heat stroke.
  • Heat stroke occurs when the body’s core temperature is higher than 104 degrees (give or take a couple of degrees, depending on the individual’s heat tolerance). Sweating stops, pulse is rapid, and the skin is flushed and dry. The person becomes delirious and may faint. About 10% of heat stroke victims die. If they survive, they often have brain damage.

Heart attacks and strokes are more common when there’s a heat wave. Heat causes the heart to work harder and faster. Even a healthy person can die of heart attack or stroke if they try to do too much outside on a hot, humid day.

The National Weather Service offers this chart to help you decide if it’s safe to be outside. Remember, these temperatures are for shady locations. If you are in direct sunlight, the heat index can be 15 degrees hotter.

Danger level              Heat Index                 Effect on the body                 

Caution                       80-90 degrees            Fatigue possible with long exposure or physical activity outdoors

Extreme caution         90-103 degrees           Cramps, heat exhaustion, heat stroke occur with long exposure or physical activity

Danger                       103-124 degrees         Heat exhaustion likely; heat stroke possible with long exposure or activity outdoors

Extreme danger         125+ degrees              Heat stroke highly likely

How do heat waves kill so quickly?

 When the body cannot cool itself by sweating or the person cannot get a break –even for a few hours of air conditioning – the body’s internal systems break down. Called hyperthermia, it’s the opposite of hypothermia that can happen during winter. Hyperthermia means the body’s temperature is dangerously high and is caused by failure of the body’s heat-regulating process.

Hyperthermia causes the body to try to cool the blood by dilating blood vessels in the skin and constricting blood vessels in the stomach. Less blood to the gut lets toxins leak into the blood. Cells begin to die, triggering a massive inflammatory response that damages the body’s tissues, organs and the kidneys start to fail. Proteins in the spleen start to clump and essentially “cook.” Toxins also enter the brain causing strokes and swelling.

This process can happen very quickly; the person may not be aware of the danger. Most heat wave deaths occur in older persons and the mentally ill. Older people have more trouble regulating their temperature and are less likely to know they are too hot. Additionally, some medicines commonly used by older people can make it harder to regulate temperature. Older people tend to be more socially isolated than younger people. Social isolation is the greatest risk factor for dying during a heat wave.

Heat survival tips

Be sure you and your family follow these 10 safety tips this summer:

  1. Start prevention early and stay hydrated by drinking half a gallon of water per day if you are indoors. To this, add 34-68 ounces of water for every hour of outdoor time, depending on how active you are. Drink before you feel thirsty. If you feel thirsty, you’re already dehydrated!
  1. You don’t need sports drinks unless you are exercising intensely for more than an hour. These drinks (like Gatorade or Pedialyte) help replace electrolytes lost through sweating and sugar that you need for energy during longer exercise sessions. Energy drinks are different from sports drinks and don’t contain electrolytes. They do contain a lot of caffeine or other stimulants, sugar and other additives. Energy drinks can raise blood pressure in people who don’t consume much caffeine.
  1. Avoid alcohol and caffeine drinks because they can cause the body to lose more fluids through urine.
  1. Wear lightweight, light-colored clothing, made of natural fabric or special fabrics designed to wick away sweat.
  1. Use a sun hat or umbrella outdoors.
  1. Eat smaller, more frequent meals.
  1. Stay indoors as much as possible. If you do not have air conditioning, try to spend at least part of the day in an air-conditioned place such as a library, shopping mall, museum or visit friends who have air conditioning. The most crucial hours to be in air conditioning are generally from 1 to 6 p.m. Fans will not prevent heat-related illness. Air conditioning is needed to remove the humidity in the air, so the body can cool itself.
  1. Avoid strenuous activity, especially during the hottest part of the day. If you must be outside, take regular breaks.
  1. Check at least daily on older people, sick or obese people and people who are socially isolated. If you are unable to contact them, go to their location or call 911 with their address for a wellness check. People with heart, lung or kidney disease; ill with a fever; or have high blood pressure, a chronic condition or poor circulation are especially vulnerable during a heat wave. Taking medications such as diuretics, sedatives, tranquilizers, and some heart and blood pressure drugs can also make a person more vulnerable to heat illness. The third day of a heat wave is critical for the human body. Those who have endured extreme heat often can no longer cope after the third day, especially if temperatures remain high at night.
  1. If you suspect someone is suffering from a heat-related problem:
  • Get him out of the heat and into a shady area or air-conditioning.
  • Urge him to lie down and loosen clothing so you can apply cool, wet washcloths directly to bare skin. For quickest blood cooling, apply to the neck, wrists, armpits and groin areas.
  • Help him to bathe or sponge off with cool water.
  • If he is conscious and can swallow safely, offer cool water, fruit or vegetable juices. No alcohol or caffeine.
  • If at any time he becomes unresponsive, confused or combative, or has trouble breathing, call 911 immediately. This is a medical emergency!


Photo by Halfpoint