Smoking is the main cause of Chronic Obstructive Pulmonary Disease (COPD). COPD is the name for a collection of lung diseases including chronic bronchitis, emphysema and chronic obstructive airways disease. At least four out of five people who develop the disease are, or have been, smokers. The lining of the airways becomes inflamed and permanently damaged by smoking. This damage cannot be reversed. Around 10-25% of smokers develop COPD.