People with chronic obstructive pulmonary disease (COPD) have airways that are narrowed and blocked due to damage. There are a few different causes of COPD.
More than 95 percent of COPD cases are caused by smoking cigarettes.
About 5 percent of cases are caused by significant exposure to various types of dust such as coal, grain, or wood or by recurrent or significant lung infections in infancy and early childhood.
Perhaps 1 percent of the cases of COPD - and about 2 percent of emphysema cases - are caused by genetic-based deficiencies in an enzyme called alpha-1 antitrypsin.