U.S. Department of Health And Human Services
Centers for Disease Control and Prevention
Heat-related deaths and illness are preventable yet annually many people succumb to extreme heat. Historically, from 1979 to 1999, excessive heat exposure caused 8,015 deaths in the United States. During this period, more people in this country died from extreme heat than from hurricanes, lightning, tornadoes, floods, and earthquakes combined. In 2001, 300 deaths were caused by excessive heat exposure.
People suffer heat-related illness when their bodies are unable to compensate and properly cool themselves. The body normally cools itself by sweating. But under some conditions, sweating just isn’t enough. In such cases, a person’s body temperature rises rapidly. Very high body temperatures may damage the brain or other vital organs.
Several factors affect the body’s ability to cool itself during extremely hot weather. When the humidity is high, sweat will not evaporate as quickly, preventing the body from releasing heat quickly. Other conditions related to risk include age, obesity, fever, dehydration, heart disease, mental illness, poor circulation, sunburn, prescription drugs, and alcohol use.
Because heat-related deaths are preventable, people need to be aware of who is at greatest risk and what actions can be taken to prevent a heat-related illness or death. The elderly, the very young, and people with mental illness and chronic diseases are at highest risk. However, even young and healthy individuals can succumb to heat’s detrimental effects if they participate in strenuous physical activities during hot weather.
Air-conditioning is the number one protective factor against heat-related illness and death. If a home is not air-conditioned, people can reduce their risk for heat-related illness by spending time in public facilities that are air-conditioned.
Summertime activity, whether on the playing field or the construction site, must be balanced with measures that aid the body’s cooling mechanisms and prevent heat-related illness. The below information goes into further detail on how you can prevent, recognize, and cope with heat-related health problems.
What Is Extreme Heat?
Temperatures that hover 10 degrees or more above the average high temperature for the region and last for several weeks are defined as extreme heat. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a “dome” of high atmospheric pressure traps hazy, damp air near the ground. Excessively dry and hot conditions can provoke dust storms and low visibility.
Droughts occur when a long period passes without substantial rainfall. A heat wave combined with a drought is a very dangerous situation.
During Hot Weather
To protect your health when temperatures are extremely high, remember to keep cool and use common sense. The following tips are important:
Drink Plenty of Fluids
During hot weather you will need to increase your fluid intake, regardless of your activity level. Don’t wait until you’re thirsty to drink. During heavy exercise in a hot environment, drink two to four glasses (16–32 ounces) of cool fluids each hour.
Warning: If your doctor generally limits the amount of fluid you drink or has you on water pills, ask how much you should drink while the weather is hot.
Don’t drink liquids that contain caffeine, alcohol, or large amounts of sugar — these actually cause you to lose more body fluid. Also avoid very cold drinks, because they can cause stomach cramps.
Replace Salt and Minerals
Heavy sweating removes salt and minerals from the body. These are necessary for your body and must be replaced. If you must exercise, drink two to four glasses of cool, nonalcoholic fluids each hour. A sports beverage can replace the salt and minerals you lose in sweat. However, if you are on a low-salt diet, talk with your doctor before drinking a sports beverage or taking salt tablets.
Wear Appropriate Clothing and Sunscreen
Wear as little clothing as possible when you are at home. Choose lightweight, light-colored, loose-fitting clothing. Sunburn affects your body’s ability to cool itself and causes a loss of body fluids. It also causes pain and damages the skin. If you must go outdoors, protect yourself from the sun by wearing a wide-brimmed hat (also keeps you cooler) and sunglasses and by putting on sunscreen of SPF 15 or higher (the most effective products say “broad spectrum” or “UVA/UVB protection” on their labels) 30 minutes prior to going out. Continue to reapply it according to the package directions.
Schedule Outdoor Activities Carefully
If you must be outdoors, try to limit your outdoor activity to morning and evening hours. Try to rest often in shady areas so that your body’s thermostat will have a chance to recover.
If you are not accustomed to working or exercising in a hot environment, start slowly and pick up the pace gradually. If exertion in the heat makes your heart pound and leaves you gasping for breath, STOP all activity. Get into a cool area or at least into the shade, and rest, especially if you become lightheaded, confused, weak, or faint.
Stay Cool Indoors
Stay indoors and, if at all possible, stay in an air-conditioned place. If your home does not have air conditioning, go to the shopping mall or public library—even a few hours spent in air conditioning can help your body stay cooler when you go back into the heat. Call your local health department to see if there are any heat-relief shelters in your area. Electric fans may provide comfort, but when the temperature is in the high 90s, fans will not prevent heat related illness. Taking a cool shower or bath or moving to an air-conditioned place is a much better way to cool off. Use your stove and oven less to maintain a cooler temperature in your home.
Use a Buddy System
When working in the heat, monitor the condition of your co-workers and have someone do the same for you. Heat-induced illness can cause a person to become confused or lose consciousness. If you are 65 years of age or older, have a friend or relative call to check on you twice a day during a heat wave. If you know someone in this age group, check on them at least twice a day.
Monitor Those at High Risk
Although any one at any time can suffer from heat-related illness, some people are at greater risk than others.
- Infants and children up to four years of age are sensitive to the effects of high temperatures and rely on others to regulate their environments and provide adequate liquids.
- People 65 years of age or older may not compensate for heat stress efficiently and are less likely to sense and respond to change in temperature.
- People who are overweight may be prone to heat sickness because of their tendency to retain more body heat.
- People who overexert during work or exercise may become dehydrated and susceptible to heat sickness.
- People who are physically ill, especially with heart disease or high blood pressure, or who take certain medications, such as for depression, insomnia, or poor circulation, may be affected by extreme heat.
Visit adults at risk at least twice a day and closely watch them for signs of heat exhaustion or heat stroke. Infants and young children, of course, need much more frequent watching.
Adjust to the Environment
Be aware that any sudden change in temperature, such as an early summer heat wave, will be stressful to your body. You will have a greater tolerance for heat if you limit your physical activity until you become accustomed to the heat. If you travel to a hotter climate, allow several days to become acclimated before attempting any vigorous exercise, and work up to it gradually.
Use Common Sense
Remember to keep cool and use common sense:
- Avoid hot foods and heavy meals— they add heat to your body.
- Drink plenty of fluids and replace salts and minerals in your body.
- Dress infants and children in cool, loose clothing and shade their heads and faces with hats or an umbrella.
- Limit sun exposure during mid-day hours and in places of potential severe exposure such as beaches.
- Do not leave infants, children, or pets in a parked car.
- Provide plenty of fresh water for your pets, and leave the water in a shady area.
Hot Weather Health
Even short periods of high temperatures can cause serious health problems. Doing too much on a hot day, spending too much time in the sun, or staying too long in an overheated place can cause heat-related illnesses. Know the symptoms of heat disorders and overexposure to the sun, and be ready to give first aid treatment.
Heat stroke occurs when the body is unable to regulate its temperature. The body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided.
Recognizing Heat Stroke
Warning signs of heat stroke vary but may include the following:
- An extremely high body temperature (above 103°F, orally)
- Red, hot, and dry skin (no sweating)
- Rapid, strong pulse
- Throbbing headache
What to Do
If you see any of these signs, you may be dealing with a life-threatening emergency. Have someone call for immediate medical assistance while you begin cooling the victim. Do the following:
- Get the victim to a shady area.
- Cool the victim rapidly using whatever methods you can. For example, immerse the victim in a tub of cool water; place the person in a cool shower; spray the victim with cool water from a garden hose; sponge the person with cool water; or if the humidity is low, wrap the victim in a cool, wet sheet and fan him or her vigorously.
- Monitor body temperature, and continue cooling efforts until the body temperature drops to 101–102°F.
- If emergency medical personnel are delayed, call the hospital emergency room for further instructions.
- Do not give the victim fluids to drink.
- Get medical assistance as soon as possible.
Sometimes a victim’s muscles will begin to twitch uncontrollably as a result of heat stroke. If this happens, keep the victim from injuring himself, but do not place any object in the mouth and do not give fluids. If there is vomiting, make sure the airway remains open by turning the victim on his or her side.
Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids.
It is the body’s response to an excessive loss of the water and salt contained in sweat. Those most prone to heat exhaustion are elderly people, people with high blood pressure, and people working or exercising in a hot environment.
Recognizing Heat Exhaustion
Warning signs of heat exhaustion include the following:
- Skin may be cool and moist
- Pulse rate will be fast and weak
- Breathing will be fast and shallow.
If heat exhaustion is untreated, it may progress to heat stroke. Seek medical attention immediately if any of the following occurs:
- Symptoms are severe
- The victim has heart problems or high blood pressure
Otherwise, help the victim to cool off, and seek medical attention if symptoms worsen or last longer than 1 hour.
What to Do
Cooling measures that may be effective include the following:
- Cool, nonalcoholic beverages, as directed by your physician
- Cool shower, bath, or sponge bath
- An air-conditioned environment
- Lightweight clothing
Heat cramps usually affect people who sweat a lot during strenuous activity. This sweating depletes the body’s salt and moisture. The low salt level in the muscles causes painful cramps. Heat cramps may also be a symptom of heat exhaustion.
Recognizing Heat Cramps
Heat cramps are muscle pains or spasms—usually in the abdomen, arms, or legs—that may occur in association with strenuous activity. If you have heart problems or are on a low-sodium diet, get medical attention for heat cramps.
- Heavy sweating
- Muscle cramps
- Nausea or vomiting
What to Do
If medical attention is not necessary, take these steps:
- Stop all activity, and sit quietly in a cool place.
- Drink clear juice or a sports beverage.
- Do not return to strenuous activity for a few hours after the cramps subside, because further exertion may lead to heat exhaustion or heat stroke.
- Seek medical attention for heat cramps if they do not subside in 1 hour.
Sunburn should be avoided because it damages the skin. Although the discomfort is usually minor and healing often occurs in about a week, a more severe sunburn may require medical attention.
Symptoms of sunburn are well known: the skin becomes red, painful, and abnormally warm after sun exposure.
What to Do
Consult a doctor if the sunburn affects an infant younger than 1 year of age or if these symptoms are present:
- Fluid-filled blisters
- Severe pain
Also, remember these tips when treating sunburn:
- Avoid repeated sun exposure.
- Apply cold compresses or immerse the sunburned area in cool water.
- Apply moisturizing lotion to affected areas.
- Do not use salve, butter, or ointment.
- Do not break blisters.
Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It can occur at any age but is most common in young children.
Recognizing Heat Rash
Heat rash looks like a red cluster of pimples or small blisters. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases.
What to Do
The best treatment for heat rash is to provide a cooler, less humid environment. Keep the affected area dry. Dusting powder may be used to increase comfort, but avoid using ointments or creams—they keep the skin warm and moist and may make the condition worse. Treating heat rash is simple and usually does not require medical assistance. Other heat-related problems can be much more severe.
Recovery and Profiling
Patients with heat stroke will require prolonged convalescence. They should receive profiles restricting heat exposure until clinical recovery is complete and their heat tolerance has been evaluated.
Heat intolerant individuals are considered to have either limited thermoregulatory response to heat stress or limited capacity for heat acclimatization and, therefore, be predisposed to heat injury. Certain diseases are well known to cause heat intolerance (a classic example is congenital ectodermal dysplasia in which sweat glands are absent). Heat stroke has been considered to be evidence for heat intolerance. However, a recent study was able to demonstrate measurable heat intolerance in only 1 of 10 individuals after recovery from heat stroke
One Last Hot Tip…
These self-help measures are not a substitute for medical care but may help you to recognize and respond promptly to warning signs of trouble. Your best defense against heat-related illness is prevention. Staying cool and making simple changes in your fluid intake, activities, and clothing during hot weather can help you to remain safe and healthy.
For more information on hot weather conditions and health, please contact:
Centers for Disease Control and Prevention
National Center for Environmental Health, MS F52
4700 Buford Hwy, Atlanta, GA 30341-3717