Summer oﬃcially started a few weeks ago, but in this part of the country hot weather isn’t limited to the oﬃcial summer season and neither is the risk of heat-related illness.
It is well known that as we age, we don’t tolerate the eﬀects of heat as well as we once did. This is due to a combination of many factors — a little less eﬀective temperature control by the central nervous system, less eﬀective radiation of heat from our skin and less sweating due to changes in our tiny peripheral blood vessels and sweat glands, and a general gradual decline in fitness (at least in some of us).
Along with these changes, the addition of illnesses and medications to treat them can increase risk of problems with heat. Folks with heart, lung or kidney problems and those on low-sodium diets are at increased risk — as are those who are obese or significantly underweight, diabetics, folks with sickle cell disease or traits, alcoholics and those with significant mental illnesses. Medications that increase risk are those that tend to dry us out, like diuretics and antihistamines, and those that may make us think less clearly such as sedatives and tranquilizers, stimulants and antipsychotic agents.
Our high humidity environment interferes with heat loss by sweating, thus increasing risk for heat-related illnesses.
Why are heat-related illnesses important? The most severe, heat stroke, kills about 500 people in the U.S. each year, most of whom are over 65. Prolonged periods of high temperature and humidity can temporarily raise death rates significantly. There were at least 35,000 excess deaths in three months in Europe during a heat wave in 2003 (some authorities place the figure at close to 80,000 excess deaths). With rising global temperatures heat-related illnesses are becoming more common.
We want to prevent heat-related illness rather than to treat it, but it requires time and preparation.
Step 1: Respect the heat. Plan an activity schedule that starts early in the cooler part of the day, or is delayed until temperatures cool in the evening. Allow time for frequent short breaks for cooling and taking in fluids.
Step 2: Drink one-third more liquid than your thirst dictates. That is usually around 1 ounce of fluid per 2 pounds of body weight per day. Natural juices, milk, soups, diluted thirst quenchers (mixed 50/50 with water) and frequent small drinks of water will do the job. Tea, coﬀee or colas may provide too much caﬀeine and cause frequent urination and increase risk of dehydration. The American College of Sports Medicine doesn’t think this risk is significant if caﬀeinated beverages are consumed regularly.
One sign of dehydration is darkening of the urine, produced in small amounts. An adequate intake of fluids keeps the urine light in color. Also, alcohol in all forms tends to increase fluid loss from the body, increasing the risk of dehydration.
Step 3: Nutrition. A well-balanced diet supplies essential protein, calories, vitamins and minerals to allow us to tolerate high heat. Small, frequent meals with plenty of fresh fruits, vegetables, dairy products and poultry will result in safe potassium levels for heart and muscle activity.
Step 4: Wear protective clothing and sunscreen when in the sun. A sunburn adds to the diﬃculty of transferring heat from the body, so use SPF 30 sunscreen on all exposed skin surfaces. Light-colored, loose-fitting, lightweight clothing reduces sun exposure to the skin and allows more heat loss than dark, tight clothing. A wide-brimmed, open-weave hat helps to keep the head cool.
Step 5: Watch for early signs and symptoms of heat illness. Headaches, dizziness, feeling faint, confusion, slowed speech or reflexes, unusual irritability, lack of concentration, hot and dry skin and/or mucous membranes, and dark urine are all warnings that the heat may be getting to you.
Step 6: Stop, rest and cool oﬀ. If any of these signs or symptoms develop, don’t take chances. Get out of the heat and into a cool place immediately. At high temperatures and even moderately elevated humidity (95 degrees+, 55 percent+) fans have limited eﬀectiveness for cooling, and at extreme levels (100 degrees+, 45 percent+) may even be counterproductive. Get into an air-conditioned space, and get medical attention if symptoms do not resolve quickly.
You can become conditioned for activity in periods of high temperature and humidity, but it requires at least 60-90 minutes per day of moderate activity in the heat for two weeks. You cannot rush the process. No one is immune to heat illness. It also appears that once you have had a heat-related illness, these problems are more likely to occur in you again.
(The Six Steps above are adapted from the S.C. Agromedicine Program brochure on heat illness, written by Dr. Simpson and the late Dr. Stanley H. Schuman.)