If You Think You Can Stand the Heat, Take Precautions
Many of us look forward to the heat of summer. Unfortunately, hot days increase the risk of heat-related illness, especially for people who are exerting themselves physically. Actively working muscles generate additional heat that, on very hot days, can raise your internal body temperature to dangerous levels.
Normally, your body gets rid of the extra heat from muscular activity by dissipating it into the cooler surrounding air. When temperatures rise, however, it is harder for this to occur. In fact, on the hottest days, the heat transfer process works in reverse, so the environment actually heats up your body.
When the body’s internal temperature rises, blood vessels in the skin begin to dilate, causing more blood to flow to the skin. This increases the amount of heat the body can lose, but it also decreases blood flow to many vital organs such as the brain, muscles, kidney and liver. If the flow is severely limited, muscles become weak, and the brain and other internal organs stop functioning properly (in severe cases, they can be permanently damaged).
It is not possible to predict exactly how an individual will respond to high heat levels. Groups that are more susceptible to heat-related illnesses include children, people with heart disease, diabetes or obesity, and pregnant women. Whether you are in one of these groups or not, you should take the following precautions if you know you’ll be exposed to high temperatures.
Drink lots of liquids. One way the body cools itself is through the evaporation of perspiration on the skin. When temperatures are high, your body can lose large amounts of fluid this way. To prevent heat illness, it is important to replace these fluids. Don’t wait until you feel thirsty to drink, because thirst is not a good indication of how much water you have lost. In fact, people who drink only to satisfy their thirst will consume about two-thirds of the water their bodies actually need. On a sunny day with temperatures of 90 degrees, a good rule is to drink at least 1 cup every 30 minutes.
Allow your body to adapt gradually to the heat. Start with relatively light activities and do them for brief periods. Gradually increase your activity level and the amount of time you spend outdoors. It usually takes several weeks to become fully adapted to the heat.
Check the temperature and humidity before you begin outdoor activities on a hot day, and recheck them every hour or two. If temperature or humidity rises abruptly, you may need to cut back your activity (a 10% increase in humidity is comparable to a three- to four-degree increase in temperature).
Take frequent rest breaks. Short breaks in a shaded or air-conditioned area will cool your body and give you a chance to replenish lost body fluids.
Modify your activity schedule. Perform strenuous activities, such as digging, manually mowing the lawn or jogging, early in the morning or late in the afternoon (preferably after sunset).
Dress appropriately. During very hot weather, avoid wearing heavy or layered clothing that retains body heat and prevents the evaporation of sweat from the skin. Wear light-colored clothing, which absorbs less sunlight and heat than darker colors.
Avoid alcohol and review the medications you take. Drinking alcohol causes dehydration and increases the risk of heat-related illness. Certain prescription and over-the-counter medications, such as antihistamines and diuretics, can also cause problems. As hot weather approaches, review the medications you take with your physician or pharmacist to be sure they will not make you vulnerable to high heat conditions.
Recognize and treat the early signs and symptoms of heat illness. Dizziness, fatigue and irritability are early signs that you may be overheating and need to slow down. You should be ready to return to your activities in 30 minutes or less if you take a break in a cool, shaded area and drink plenty of water. Failure to slow down can result in heat exhaustion.
Heat stroke, the most severe form of heat illness, can be life-threatening. Heat-stroke victims may complain of headache or dizziness, appear confused, behave irrationally or experience seizures. Their skin is typically pale and dry; their temperature 104 degrees or higher. If you suspect someone has heat stroke, get emergency medical attention immediately. Body temperature must be lowered as quickly as possible to prevent damage to internal organs.
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Dr. Jonathan Fielding is the director of public health and the health officer for the Los Angeles County Department of Health Services. Valerie Ulene is a board-certified specialist in preventive medicine practicing in Los Angeles. They can be reached at ourhealth@dhs.co.la.ca.us. Our Health runs the second and fourth Mondays of each month.
