Soldiers returning from deployment to South West Asia commonly report new respiratory symptoms. Inhalational lung injuries from respiratory toxins are suspected and we hypothesize that these toxins injury airway club cells and result in chronic bronchiolitis which is characterized by a persistently abnormal immune response and scarring within small airways. In this funding period, we have shown that specific and repetitive club cell injury in mice results in chronic bronchiolitis as evidenced by weight loss, airway thickening, increased lung collagen deposition, and an accumulation of alternatively-activated lung macrophages. Efforts to identify potential biomarkers of chronic bronchiolitis present in the lung lavage fluid or peripheral blood are in progress. We have also achieved numerous administrative requirements so that we can begin to determine whether parametric response mapping, a novel CT analytical technique, can identify airway abnormalities on CT scans obtained from a cohort of symptomatic Gulf War Veterans evaluated at the Airborne Hazards Clinic of Excellence located in the New Jersey War Related Illness and Injury Study Center.