Chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is a common lung disease. Having COPD makes it hard to breathe.

There are two main forms of COPD:

Chronic bronchitis, which involves a long-term cough with mucus
Emphysema, which involves damage to the lungs over time
Most people with COPD have a combination of both conditions.

Causes
Smoking is the main cause of COPD. The more a person smokes, the more likely that person will develop COPD. But some people smoke for years and never get COPD.

If a person has a rare condition in which they lack a protein called alpha-1 antitrypsin, they can develop emphysema even without smoking.