Asthma is an inflammatory condition of the lower airway characterized by airway hyperresponsiveness and bronchoconstriction. Asthma is a common condition in the United States, affecting between 7 and 8% of the population. Asthma is a heterogeneous disease, varying in symptoms and severity as well as varying in frequency of events and provocation of events. Triggers can include allergies, exercise, occupational exposures, GERD, temperature and humidity extremes, and can vary in adults and children.