Introduction: Chronic obstructive pulmonary disease in non-smokers has been an importantconcern in past decade. We studied the risk factors responsible for more severe Chronic obstructivepulmonary disease. Identifying them would help to work against progression to more severe diseaseas well as prevention.Methods: A prospective cross sectional study was done in outpatient clinic of Jinnah postgraduatemedical center from December 2010 to December 2011. All patients fulfilling the criteria for Chronicobstructive pulmonary disease were taken in study. Patients with less than five pack years smokingwith other risk factors for Chronic obstructive pulmonary disease were evaluated.Results: Out of total 90 patients, 74 (82.2%) had mild chronic obstructive pulmonary disease and 16(17.7%) had moderate to severe chronic obstructive pulmonary disease. Patients with single biomassexposure were found to have mild chronic obstructive pulmonary disease except those havingmosquito coil exposure. Patients with mosquito coil and wood smoke exposure were observed tohave moderate to severe chronic obstructive pulmonary disease (p-value 0.009).Conclusions: Wood smokewith mosquito coil smoke exposure is responsible for more severe chronicobstructive pulmonary disease._______________________________________________________________________________________Keywords: biomass; chronic obstructive pulmonary disease; non-smoker; tuberculosis.