Ask the Experts - Questions about cold weather and asthma

Allen J. Dozor, MD, is professor of pediatrics and chief of pediatric pulmonology, allergy, and sleep medicine at New York Medical College in Valhalla, N.Y., and associate physician-in-chief at Maria Fareri Children’s Hospital at the Westchester Medical Center in Valhalla.

Q. What precautions should people with asthma take when exercising outdoors in winter?

A. When a person is exercising really hard, they are breathing between 60 and 80 quarts of air per minute compared to less than 10 quarts per minute at rest. All that cold air is a significant stress that triggers narrowing of the bronchial tubes, the hallmark of asthma. The most notorious triggers include any outdoor sport in which you run long and hard,such as soccer and lacrosse. Baseball and swimming usually don’t trigger asthma, although exposure to chlorine may trigger it in some patients. (See “Get Out of the Pool, Baby” on page 9.) The good news is that exercise-induced asthma can be completely controlled as long as you keep a few things in mind:

• Make aerobic exercise part of your life year round. If you’re in better physical condition, you’ll hyperventilate less when you exercise and less cold air will enter your lungs and trigger asthma.

• Breathe in through your nose and out through your mouth.The nose’s job is to warm and humidify inhaled air before it hits the lungs.The longer you can run while breathing in through your nose, the less exercise-induced asthma you’ll have.

• Make sure your asthma is under control before you start to exercise.

Q. How does cold weather affect the lungs?

A. Some studies suggest that changes in weather or in barometric pressure may trigger asthma, but there isn’t enough good research to verify this. That said, exercising in cold air is more likely to trigger wheezing than exercising in warm air. That’s why most people with asthma have relatively few problems in the summer. However, there are many other triggers for asthma, including colds and other viral infections, which are highly contagious.

Cold weather contributes to the sudden increase in respiratory-tract infections because everyone stays indoors more. It’s important to note that this yearly cycle happens in every climate; people have just as much asthma in Florida as they do in New York. Finally, if the most important trigger for asthma is viral infections, the second most important is allergies. Dust and mold spores are the two most common indoor allergens, and if it’s cold outside and you close your windows and turn on the heat, your exposure to these allergens increases significantly.

Q. Do people with asthma need to change their medication regimens in cold weather?

A. Many people with asthma decrease their medications during the summer. Therefore, everyone should see their asthma specialist at least twice a year to review the success of their medical regimen in the past six months and to make necessary adjustments.