Another objective of this study is to investigate the relationship between small airway resistance and inflammation. The measurement of exhaled nitric oxide (FENO), a marker of inflammation, at multiple exhalation flow rates allows the partitioning of NO produced in the central airways from that generated in the more peripheral lung. We will investigate the relationship between the levels of peripheral airway NO and small airway resistance as assessed by IOS and plethysmography. Furthermore, we would like to measure bronchial blood flow (Qaw) which also is a marker of inflammation and may play a role in the narrowing of the small airways