For the past 15 years, an epidemic of asthma has been occurring in the United States. Although asthma has become a major public health problem affecting Americans of all ages, races, and ethnic groups, children have been particularly severely affected. The epidemic is most severe among lower income and minority children. Physicians don't know the main cause of asthma, but they do know that the tendency to develop asthma is often inherited. All children with asthma have airways that are overly sensitive, or hyper-reactive, to certain asthma triggers .
Some common triggers are exercise, allergies, viral infections, and smoke.
The sensitive airway linings react to trigger exposure by becoming inflamed, swollen, and filled with mucus. The muscles lining the swollen airways tighten and constrict, making them even more narrowed and obstructed. These reactions, in turn, can cause coughing, wheezing, chest tightness, and shortness of breath. The symptoms, frequency, severity and duration of an asthma episode also vary from child to child. Over the past 15 years, there have been major advances in the scientific understanding of asthma.