A Guide to COPD: What Is Chronic Obstructive Pulmonary Disease? 

Medically Reviewed by Dr. Samantha Miller

Photo Courtesy: Phynart Studio/E+/Getty Images

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory condition of the lungs. As a progressive condition, COPD worsens over time, making it difficult to breathe. Often, COPD is accompanied by a cough, wheezing, shortness of breath, and/or chest tightness. 

According to the World Health Organization, over 250 million people worldwide have COPD — with 65 million having moderate to severe COPD. More than 90% of deaths from COPD occur in low- and middle-income countries, where strategies for prevention and control are often lacking. 

It is also one of the most common forms of lung disease in the United States, causing more than 150,000 deaths in 2018, making it the third leading disease-related cause of death. Although COPD impacts people of all genders, at one time COPD was most common in men. But due to an increased use of tobacco products and a higher risk of exposure to indoor air pollution — such as fuels used for cooking and heating — in low-income countries, the disease now affects men and women almost equally.

As mentioned above, COPD is characterized by breathing problems caused by blockage and constriction of the airways. COPD causes the lungs to lose their natural elasticity, which impairs the ability to inhale and exhale fully. Three of the most common subtypes of COPD are emphysema, chronic bronchitis, and serious cases of asthma. Often, an affected individual will have a combination of these subtypes.

  • Emphysema arises when the alveoli (air sacs) at the end of the smallest air passages (called the bronchioles) of the lungs are damaged by exposure to cigarette smoke or other irritating gases and particulate matter (such as air pollution). This damage prevents the exchange of air and CO2 in the lungs, leading to shortness of breath and the struggle for oxygen.
  • Chronic bronchitis is an inflammation of the bronchial tubes that carry air to and from the alveoli of the lungs. It is characterized by daily cough and mucus production. 
  • Serious cases of asthma also involve chronic inflammation and narrowing of the airway due to excess mucus production.