COPD: Causes Make an Appointment Refer a Patient Ask a Question Reviewed by Irina Petrache, MD, Russell P. Bowler, MD, PhD (March 01, 2021) Chronic obstructive pulmonary disease (COPD) is not contagious, so what are the causes of COPD? More than 85 percent of COPD cases in the US 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. Long-term exposure to air pollution or chemical fumes can also cause COPD. Some people who have asthma can develop COPD. About 1-2 percent of COPD cases are caused by genetic-based deficiencies in an enzyme called alpha-1 antitrypsin. In these people COPD may begin at a young age. People with COPD can also have exacerbations (flare-ups), which are periods of restricted breathing that can be severe. COPD exacerbation is most often caused by an infection, either in the lungs or the body, which causes inflammation in the lungs. COPD exacerbations can also be caused by a person with COPD continuing to smoke tobacco. Chronic obstructive pulmonary disease affects more than 24 million people in the United States. Most people who have COPD are at least 40 years old when symptoms begin. COPD is the fifth 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. COPD: Symptoms Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.