Causes and Risk Factors

Causes

Most cases of COPD develop after long-term exposure to lung irritants that damage the lungs and the airways.

In the United States, the most common irritant that causes COPD is cigarette smoke. Pipe, cigar, and other types of tobacco smoke also can cause COPD. Secondhand smoke—that is, smoke in the air from other people smoking—also can irritate the lungs and contribute to COPD.

Breathing in air pollution and chemical fumes or dust from the environment or workplace also can contribute to COPD.

In approximately one percent of cases for people with COPD, a genetic condition called alpha-1 antitrypsin deficiency may play a role in causing COPD. People who have this condition have low levels of alpha-1 antitrypsin (AAT)—a protein made in the liver.

Having a low level of the AAT protein can lead to lung damage and COPD if you're exposed to smoke or other lung irritants. If you have this condition and smoke, COPD can worsen very quickly.

Risk Factors

The main risk factor for COPD is smoking. Most people who have COPD smoke or used to smoke. People who have a family history of COPD are more likely to get the disease if they smoke. Women who smoke may have a higher risk of developing COPD, as women are more susceptible to the effects of smoke.

Long-term exposure to other lung irritants also is a risk factor for COPD. Examples of other lung irritants include air pollution and chemical fumes and dust from the environment or workplace.

Most people who have COPD are at least 40 years old when symptoms begin. Although it isn't common, people younger than 40 can have COPD. For example, this may happen if a person has alpha-1 antitrypsin deficiency, a genetic condition.