Respiratory tract impairments are diseases that affect the air passages, including the nasal passage, the bronchi and the lungs. They range from acute infections, such as pneumonia and bronchitis, to chronic conditions such as asthma and chronic obstructive pulmonary disease.

Asthma is a disease which causes constriction of airways resulting in wheezing, shortness of breath, a sensation of chest tightness and cough, frequently worse in early morning or nighttime.  Common triggers include exertion, exposure to cold air, tobacco smoke and other irritants and allergens such as pet dander and mold spores.  Avoiding triggers may help prevent flare ups. The National Center for Health Statistics reports that 17.7 million adults and 6.3 million children currently have asthma. Medications can reverse the acute bronchial constriction as well as decrease the abnormal hypereactivity. Many of these are inhaled. If asthma is treated aggressively within the first few years a child has a good chance of growing out of it but if inadequately treated the airways remodel and the disease can be lifelong.