Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease that causes obstructed airflow from the lungs. Symptoms include breathing difficulty, cough, mucus (sputum) production and wheezing. Smoking is the main cause of COPD and is thought to be responsible for around 9 in every 10 cases. The harmful chemicals in smoke can damage the lining of the lungs and airways and for more information visit:https://www.resmed.co.in/respiratory-care/copd/what-is-chronic-obstructive-pulmonary-disease