If you live in an urban area, you may be especially prone to develop heat exhaustion during a prolonged heat wave, particularly if there are stagnant atmospheric conditions and poor air quality. In what is known as the 'heat island effect,' asphalt and concrete store heat during the day and only gradually release it at night, resulting in higher nighttime temperatures.

Other risk factors associated with heat-related illness include:

Age
Infants and children up to age 4, and adults over age 65, are particularly vulnerable because they adjust to heat more slowly than other people.

Health Conditions 
These include heart, lung, or kidney disease, obesity or underweight, high blood pressure, diabetes, mental illness, sickle cell trait, alcoholism, sunburn, and any conditions that cause fever. People with diabetes are at increased risk of emergency room visits, hospitalization, and death from heat-related illness and may be especially likely to underestimate their risk during heat waves.

Medications
These include some medicines in the following classes: diuretics, sedatives, tranquilizers, stimulants, heart and blood pressure medications, and medications for psychiatric conditions.

Check with your doctor to see if your health conditions and medications are likely to affect your ability to cope with extreme heat and humidity.

Preventing Heat Exhaustion

When the heat index is high, it's best to stay inside in air conditioning. If you must go outdoors, you can prevent heat exhaustion by taking these steps:

• Wear lightweight, light-colored, loose-fitting clothing, and a wide-brimmed hat.
• Use a sunscreen with an SPF of 30 or more.
• Drink extra fluids. To prevent dehydration, drink plenty of water, fruit juice, or other liquid without alcohol or caffeine. Because heat-related illness also can result from salt depletion, it may be advisable to substitute an electrolyte-rich sports drink for water during periods of extreme heat and humidity. Ask your doctor about the best types of fluid and how much you should be drinking.
• A general recommendation for those doing moderate to high-intensity exercise should drink around seventeen to twenty ounces of fluid two to three hours before exercise, and consider adding another eight ounces of water or sports drink right before exercise. During exercise, you should consume another seven to ten ounces of water every twenty minutes, even if you don't feel thirsty. Also, drink another eight ounces within a half hour after exercise. Take additional precautions when exercising or working outdoors. All of these numbers are approximate and should be tailored to your needs.
• Avoid fluids containing caffeine or alcohol, because both substances can make you lose fluids and worsen heat exhaustion. If you have epilepsy or heart, kidney, or liver disease, are on a fluid-restricted diet, or have a problem with fluid retention, check with your doctor before increasing liquid intake.
  
  

Recap on Treating Heat Exhaustion

• Drink plenty of fluid.
• Remove any tight or unnecessary clothing.
• Take a cool shower, bath, or sponge bath.
• Apply other cooling measures such as fans or ice towels.

If such measures fail to provide relief within 15 minutes, seek emergency medical help, because untreated heat exhaustion can progress to heat stroke.

After you've recovered from heat exhaustion, you'll probably be more sensitive to high temperatures during the following week. So it's best to avoid hot weather and heavy exercise until your doctor tells you that it's safe to resume your normal activities. 

Most importantly, have fun this summer, stay cool, and make sure you have a first aid kit!