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Epidemiology of Chronic Obstructive Pulmonary Disease. Chronic obstructive pulmonary disease (COPD) affects about 300 million people worldwide, resulting in approximately 64 million disability-adjusted life years. Household air pollution affects almost 3 billion people worldwide and is a major risk factor for COPD. An estimated 25% to 45% of patients with COPD worldwide have never smoked. Fourteen percent of the overall COPD burden is attributable to occupational exposures. Rural populations are at higher risk for COPD than urban residents. African American never-smokers have a disproportionately high prevalence and Hispanic people have a low prevalence of COPD.