Definition of Chronic obstructive pulmonary disease:

Chronic obstructive pulmonary disease (COPD) is lung disease that makes it difficult to breathe. There are two main forms of COPD:

• Chronic bronchitis, which causes long-term swelling and a large amount of mucus in the main airways in the lungs
• Emphysema, a lung disease that destroys the air sacs in the lungs

Most people with COPD have symptoms of both.

Causes, incidence, and risk factors:

Smoking is the leading cause of COPD. The more a person smokes, the more likely that person will develop severe bronchitis. Secondhand smoke may also cause chronic bronchitis. Air pollution, infection, and allergies make chronic bronchitis worse.

In rare cases, nonsmokers who lack a protein called alpha-1 antitrypsin can develop emphysema.

Other risk factors for COPD are:

• Exposure to certain gases or fumes in the workplace
• Exposure to heavy amounts of secondhand smoke and pollution
• Frequent use of cooking gas without proper ventilation