Project Summary Our long-term goal has been to characterize the heterogeneous group of chronic lower airway diseases (LAD) observed in World Trade Center (WTC) workers and volunteers, uncover their risk factors and comorbidities, identify subgroups with adverse and favorable lung function trajectories and outcomes, deploy novel imaging approaches to the investigation of the underlying lung injury, and improve surveillance and prevention strategies. Our previous research suggests the differential adverse effects and imaging characteristics of the longitudinal lung function trajectories of the WTC workers, and markers suggesting early chronic disabling lung disease. We thus propose to test the use of added respiratory surveillance tools and explore functional markers of disease progression, explore alternate methods to investigate longitudinal functional trajectories, and novel spirometry calibration methods that might facilitate the implementation of spirometry in nonspecialized settings. This project will be conducted in the occupational cohort followed at Mount Sinai, among the WTC Pulmonary Evaluation Unit Chest CT Imaging Archive subcohort members still on active health surveillance. This group of 1710 WTC workers has detailed disease symptom, both pre-WTC and WTC-related occupational exposure, longitudinal spirometry measurements and body weight trends, visual chest CT imaging classification and grading, and quantitative computer tomography (QCT) measurements of airway, body composition, and pulmonary parenchymal and vascular abnormalities.