We have known for more than 25 years that exercise-induced asthma is caused by breathing dry, cold air, but for the first time we may know why this happens. Researchers at the Naval Medical Center-San Diego have just shown that exercise-induced asthma is associated with diminished secretion of lung mucous ( Chest, September 2008). These same people also produce far less saliva, sweat and tears.
So when certain susceptible people breathe hard and fast, in air that is cold and dry, the bronchial tubes are not protected by an adequate supply of mucous in their lungs. This irritates the bronchial tubes to cause wheezing, coughing and shortness of breath. People who are least likely to suffer exercise-induce asthma would therefore be those who produce large amounts of lung mucous, sweat, saliva and tears. Late-onset asthma in adults