Chronic Obstructive Pulmonary Disease is the progressive lung disease causing chronic airflow limition, is caused due to smoking which is approx. 80-90% of cases, air pollution specifically due to particulate matter, chemicals, occupational exposures, due to genetical cause alpha-1 antitrypsin deficiency. According to pathophysiology inflammation, airway narrowing, mucus hypersecretion, lung tissue damage can also lead to COPD.