Updated March 12, 2015.

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Definition: Emphysema

Emphysema is a chronic lung disease caused by damage to the alveoli, the tiny air sacs in the lung where exchange of oxygen and carbon dioxide takes place. With emphysema, damage to the alveoli results in air becoming trapped, causing them to expand and rupture.

Emphysema is one type of chronic obstructive pulmonary disease (COPD), a category of lung diseases that also includes chronic bronchitis and bronchiectasis.

The most common symptom is shortness of breath. The most common cause is smoking, but exposure to secondhand smoke and air pollution, as well as the inherited disorder alpha-1-anti-trypsin deficiency, are additional important causes.

Emphysema is irreversible and progressive over time. People with emphysema are also at increased risk of developing lung cancer. Quitting smoking is very important for individuals living with this condition, and can help to slow the progression of the disease.