What Causes COPD?

Smoking Is the Most Common Cause of COPD

Most cases of chronic obstructive pulmonary disease (COPD) develop after repeatedly breathing in fumes and other things that irritate and damage the lungs and airways. Cigarette smoking is the most common irritant that causes COPD. Pipe, cigar, and other types of tobacco smoke can also cause COPD, especially if the smoke is inhaled. Breathing in other fumes and dusts over a long period of time may also cause COPD. The lungs and airways are highly sensitive to these irritants. They cause the airways to become inflamed and narrowed, and they destroy the elastic fibers that allow the lung to stretch and then return to its resting shape. This makes breathing air in and out of the lungs more difficult.

Other things that may irritate the lungs and contribute to COPD include:

• Working around certain kinds of chemicals and breathing in the fumes for many years
• Working in a dusty area over many years
• Heavy exposure to air pollution

Being around secondhand smoke (smoke in the air from other people smoking cigarettes) also plays a role in an individual developing COPD.

Genes—tiny bits of information in your body cells passed on by your parents—may play a role in developing COPD. In rare cases, COPD is caused by a gene-related disorder called alpha 1 antitrypsin deficiency. Alpha 1 antitrypsin (an-te-TRIP-sin) is a protein in your blood that inactivates destructive proteins. People with antitrypsin deficiency have low levels of alpha 1 antitrypsin; the imbalance of proteins leads to the destruction of the lungs and COPD. If people with this condition smoke, the disease progresses more rapidly.