DEAR DR. DONOHUE: What is the proper way to cool off during outdoor activities in the summer? The other day it was very hot, and my husband and I played golf. To stay cool, we poured cold water from the water cooler on our heads. Does this present any danger? Someone expressed a concern that it could cause a stroke. – J.W.

ANSWER: Some of this might not be applicable to you, since summer is drawing to a close, but it applies to others who are beginning a vigorous training session, like football players, in what will still be hot weather.

Heat acclimatization is most important. People get used to heat by gradually increasing the time they spend exercising in it. It takes 10 days to two weeks for the body to acclimatize. Once it has, the body learns how to cope with heat. For one thing, sweating begins earlier.

Hot-weather exercise requires people to drink lots of fluid. If you weigh yourself before and after exercise, you can get a rough approximation of how much fluid you need during exercise. A 1-pound weight loss represents a loss of 16 ounces of fluid. People should try to replace that while they are exercising. Cold water is a good replacement fluid. However, if you are exercising hard for much more than one hour and if you’re sweating profusely, you need to put salt in the water, or you should drink a sports drink that has sodium and potassium in it.

Protect yourself from the sun with lightweight, white garments. White reflects sunlight.

Pouring cold water from a water cooler on your head is a good idea. It’s not dangerous. It won’t give you stroke. Recognize some of the danger signals of prolonged heat exposure. The first sign of trouble is muscle cramps. The next step is profuse sweating, nausea and lightheadedness. For both situations, stop, drink cold drinks, get into the shade or take a break so you can find an air-conditioned place to cool down. The most serious heat injury is heat stroke, which occurs when body temperature rises above 104 F (40 C). People become confused, delirious and can slip into a coma. This is an emergency. Body temperature must be lowered quickly by plunging the person into a bath of cold water with a temperature around 35.6 F (2 C).

DEAR DR. DONOHUE: My teenager seems always to get swimmer’s ear, even after one day of swimming. What can be done about it? – K.C.

ANSWER: Water trapped in the ear canal causes swimmer’s ear. Water removes the protective wax layer of the ear canal and promotes the growth of bacteria and fungi. The major symptom is an itchy ear.

Your teenager has to be most careful to get all the water out of the ears after a swim. Gently inserting the corner of a towel into the ear canal can wick water out of it. Don’t use a cotton-tipped applicator. It can damage the canal. Make a solution of equal parts white vinegar and rubbing alcohol. Put one or two drops into the ears after swimming and let the drops stay there for two or three minutes. Then tilt the head to one side to drain them out. The solution restores acid balance to the ear canal and dries it. If the ear hurts or if the condition lasts and lasts, then a doctor has to examine the ear and prescribe the proper antibiotic drops.

DEAR DR. DONOHUE: I fish in a remote lake every summer with a group of men. I am a mosquito magnet. My friends say something in my skin attracts them. What can I do about it? Someone has suggested B vitamins. – C.J.

ANSWER: Mosquitoes are attracted by the carbon dioxide we exhale, but everyone produces just about the same amount of it. They’re also attracted by lactic acid secreted by the skin. Some people do secrete more than others, and that can make them mosquito targets.

Insect repellent with 20 percent DEET is quite effective and lasts four hours.

Two products newly marketed in the U.S. are also good. One is Cutter Advanced, which contains picaridin. The other is Repel Lemon Eucalyptus, which has oil of lemon eucalyptus. They both last about four hours, too.

B vitamins don’t work.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.