Subjects will be evaluated and then categorized based on the National Asthma Education and Prevention Program (NAEPP) guidelines. We will measure the pH from EBC in children age 6 to less than 18 years of age and compare findings to clinical data, spirometry, and expired NO. In this way, we will determine if EBC is a potentially useful non-invasive measurement of airway disease. It is hoped that measurements of EBC will be helpful in identifying those children in which the addition of an anti-inflammatory medication is appropriate. We will also attempt to measure inflammatory mediators to determine if they can be used to assess inflammation.