Determination of pH in EBC is a novel, non-invasive technique in clinical study as a means to evaluate the severity of pulmonary inflammation. In the protocol described, we will evaluate the utility of EBC in the measurement of airway disease in 60 children with asthma and compare them to 30 healthy cohorts in the same age range. We will determine if EBC pH is reflective of the degree of morbidity in children by correlating measurements with known parameters of disease including: 1) number of hospitalizations, 2) absenteeism from school, 3) number of asthma exacerbations, 4) loss of work days (if applicable), 5) extent of rescue medication usage, 6) spirometry to evaluate obstruction, and 7) NO as a measurement of inflammation.