“Chronic obstructive pulmonary disease (COPD) is characterised by poorly reversible airflow obstruction and an abnormal inflammatory response in the lungs.  The latter represents the innate and adaptive immune responses to long term exposure to noxious particles and gases, particularly cigarette smoke. People with COPD are at increased risk of developing heart disease, lung cancer and a variety of other conditions especially if its due to smoking.  Inflammation is present in the lungs, particularly the small airways, of all people who smoke. This normal protective response to the inhaled toxins is amplified in COPD, leading to tissue destruction, impairment of the defence mechanisms that limit such destruction, and disruption of the repair mechanisms. In general, the inflammatory and structural changes in the airways increase with disease severity and persist even after smoking cessation.”

National Library of Medicine NIH