Metabolomics is a large-scale approach to monitoring as many as possible of the compounds involved in cellular processes in a single assay to derive metabolic profiles. Compared with genomics or proteomics, metabolomics reflects changes in phenotype and therefore function. Collection of exhaled breath condensate (EBC) is a newly developed, noninvasive method that may allow clinicians and researchers to assess biochemical profiles in the alveolar lining fluid. The aims of this study are: (1)Collecting and metabolomic profiling of the EBCs from patients with COPD/bronchiectasis; (2) Comparing the profiles of these patients obtained during stable and acute exacerbation periods; (3) Comparing the profiles of these patients with and without Pseudomonas colonization/infection; (4) Correlation of EBC metabolomic profiles with clinical phenotypes, severity and outcomes of these patients.