The occurrence of COPD in never-smokers is not widely studied, despite the fact that the relative burden of COPD in never-smokers is high in developing and developed countries, accounting for about 30% of all COPD in the community. Tobacco smoking has been an established risk factor for COPD for over five decades and virtually all our knowledge about the clinical, physiological, pathological and radiological features of COPD, as well as rates of decline in lung function and efficacies of various treatments is based on this population.  Exposure to biomass smoke during cooking in poorly ventilated homes, high levels of ambient air pollution, occupational exposures to dust and gases, ambient ozone exposure, poverty, repeated respiratory tract infections during childhood, poorly controlled chronic persistent asthma and previous tubercular lung disease are also non-smoking risk factors for COPD. Despite the relatively high burden of COPD among never smokers, relatively little is known about this phenotype. To address this issue, we will undertake a prospective observational study to investigate the differences in clinical, physiological, radiological, and blood markers between smoking (S-COPD) and non-smoking COPD (NS-COPD) subjects.