Wintertime Wheezing
Coping with asthma in cold weather

Kristin Jenkins

It’s a cold, crisp winter morning. Though the outdoor temperature is well below freezing, the sun is shining as you head out for your 30-minute run. Five minutes after you finish, your chest tightens up. A tickly feeling in your chest makes you cough. Every time you take a breath, you wheeze. You haven’t had asthma in years, so what gives? Cold-weather, exercise-induced asthma is what gives. Even if you’ve never had full-blown asthma, your airways may be very sensitive to changes in temperature and air moisture. Cold, dry air breathed in through the mouth bypasses the usual “air-conditioning” action of the nose, which warms and moisturizes the air before it goes to the lungs.

This triggers the release of certain chemicals, including leukotrienes, which constrict the airways, causing them to go into spasm. Swimmers don’t get exercise-induced asthma, points out Dr. Robert Schellenberg, head of the department of allergy and immunology at the University of British Columbia (UBC) in Vancouver, “because they are breathing in moist air.”

Here’s another scenario: a 12-year-old girl is one of the best hockey players on her team. Away from the rink, her asthma appears to be well controlled, and she rarely has a full-blown attack. But all it takes is a couple of minutes on the ice for her to start wheezing.

Strenuous activity and rapid inhalation, often through the mouth, of the cold, dry air at the rink is acting as a trigger for exercise-induced asthma, notes Dr. Charles Frankish, a clinical professor of allergy and clinical immunology at the University of Ottawa.

Even though this young hockey player doesn’t experience asthma symptoms when she’s off the ice, she may still have chronic airway inflammation. This may be due to an ongoing allergic trigger such as a pet or a viral infection such as a cold or the flu. Either way, the frequent appearance of symptoms with exercise means that her asthma is not under good control, explains Dr. Donald Stark, clinical associate professor of immunology and allergy at UBC.

“People may be tolerant of indoor asthma triggers such as mould or dust mites,” he explains. “But constant exposure to these allergens can make them more sensitive to cold, dry air when they go outside.”

In effect, cold air becomes the proverbial straw that breaks the camel’s back. “Patients think, Oh, I don’t have a problem with my cat at home, but when I go outside for a run, I get asthma,” Schellenberg points out. Adds Frankish: “If a person’s trigger factor for asthma is mainly exercise in cold air, that individual has chronic twitchiness of the airways, which may be aggravated by environmental allergens such as dust.” The impact of such allergens should be kept under control with regular use of anti-inflammatory medication.

You can reduce the risk of an exercise-related attack with specific strategies and/or drugs. “Speak to your family physician or a lung specialist about adjusting your meds to facilitate exercise.” If an activity triggers wheezing, adds Stark, “Don’t forgo exercise. Adjust the activity.”

Fortunately, bouts of asthma induced by exercise do not appear to worsen underlying asthma. The same, however, cannot be said for repeated challenges from allergens. These continually fuel airway inflammation and can have long-term consequences, so take steps to reduce exposure (see “Indoor foes”).

Bottom line: if your asthma is under good control, you should be able to be active in any weather.

Unfortunately, a 2002 survey found that in 50% of asthmatic Canadians the condition is poorly controlled, although 90% believe it is being well managed. What’s more, physicians in this country markedly overestimate both how well their patients’ asthma is controlled and how well patients understand their condition. Asthmatics are tolerating their symptoms by learning to live with lifestyle limitations.

An estimated three million Canadians have asthma, and the vast majority of them will require long-term maintenance

“But asthma should never be a reason not to exercise,” says Frankish. So check out our tips for being physically active in cold weather. “The goal is to let patients do what they want and as much as they want in terms of exercise,” says Schellenberg.

For more information, contact the Canadian Lung Association at 1 800 566 5864 or go to www.asthma.ca.

• Use an inhaled beta-2 agonsist reliever medication 20 minutes before exercising.

• Consider less strenuous forms of outdoor exercise (a brisk walk instead of a jog), or choose an indoor activity such as swimming or basketball.

• Make a point of breathing through your nose so the air gets warmed and moistened before entering your lungs.

• If you need to breathe through your mouth on a cold day, wear a scarf or a special cold-weather mask.

• Ask your doctor if you need an increased dose of your preventive anti-inflammatory medication for winter.

• Carry your inhaler close to your body as warm medication gets into the respiratory system faster.

Indoor Foes

Indoors, you face other challenges, such as dust mites, cockroaches, mould and pet parts (dander, saliva, oil secretions, feces and urine). These can trigger allergy-induced asthma. To counter these, the Asthma Society of Canada (www.asthma.ca) offers the following recommendations.

• Remove carpeting from the home, particularly in the bedroom.

• Vacuum floors, furniture and drapes frequently using a unit with a high-efficiency particulate air (HEPA) filter or a central vacuum system with an outdoor exhaust.

• Dust with a damp cloth to reduce airborne particles.

• Encase your mattress, box spring and pillows in mite-proof covers.

• Use an air cleaner in the bedroom.

• Do not allow any smoking in your home.

• To kill mites, wash your bedding in very hot water (550#C).

• Remove any pets that trigger symptoms.

• Do not use a wood stove or fireplace.

• Wash your hands frequently to reduce risk of colds and flu.

What does well-controlled asthma look like?

• You rarely experience symptoms.

• You sleep through the night.

• You exercise, even in cold air, without getting symptoms.

• You relieve symptoms with an inhaled beta-2 agonist no more than three times a week (not including protective use before exercise).

• You never miss a day of work or school because of asthma.

Anatomy of an attack

An asthma flare-up is usually caused by one or more triggers that result in obstruction of the flow of air as it passes into or out of the lungs. There are two kinds of challengers: allergic triggers, which involve the immune system, and symptom triggers, which do not.

Allergic triggers cause chronic swelling and reddening of the lining of the respiratory tract, including the trachea (windpipe), bronchi (large airways; singular = bronchus) and the broncheoles (small airways). The mucus thickens and the airways become narrower and constrict in what is known as bronchospasm. The airways may also produce more mucus, which further restricts breathing. In winter, indoor moulds, dust mites, animal dander and cockroaches are allergens that produce this kind of inflammatory response. In spring, summer and fall, asthma is often brought on by outdoor allegens such as pollen.

Symptom triggers are non-allergenic irritants that also cause the muscles surrounding the airways to twitch and constrict. These triggers include exercise, smoke, cold air, chemical fumes, industrial particles in outdoor air, strong scents such as perfume, food additives such as sulphites, and intense emotions (anger, for example). Symptom triggers are particularly adept at causing an asthma attack when the airways are chronically inflamed. This is likely to be the case when preventive anti-inflammatory steroid medication is not used regularly and underlying inflammation in the airways is poorly controlled.