COPD is a progressive, largely irreversible airflow limitation characterized by chronic cough, sputum production, and dyspneamost commonly due to smoking. Spirometry (FEV FVC < 0.7) confirms diagnosis; smoking cessation is the most effective Inhale, Exhale, Repeat: Understanding COPD ENCORE Research Group Patient Basics: Chronic Obstructive Pulmonary Disease (COPD) 2 Minute Medicine Electronic cigarette use and its association with asthma, chronic obstructive pulmonary disease (COPD) and asthma COPD overlap syndrome among never cigarette smokers Research Shows Emphysema More Common in Marijuana Smokers Than Cigarette Smokers