Reviewed by Barry J. Make, MD, Irina Petrache, MD

Chronic obstructive pulmonary disease affects more than 24 million people in the United States. It is the third leading cause of death in the U.S. Its prevalence is declining in men, many of whom quit smoking over the past several decades. Its prevalence is increasing in women, reflecting the fact that more women began to smoke at about the same time many men began to quit. The lag time between when a person began to smoke and the development of COPD is 10 or more years.

Chronic obstructive pulmonary disease (COPD) is not contagious, so what are the causes of COPD?

  • More than 85 percent of COPD cases are caused by smoking cigarettes. Being exposed to secondhand smoke (either cigarette smoke or wood smoke in developing countries) for long periods of time, including during childhood, is also known to cause COPD.

  • Other 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.

  • About 1-2 percent of COPD cases are caused by genetic-based deficiencies in an enzyme called alpha-1 antitrypsin.

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