COPD Causes and Risk Factors

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Cigarette smoking is the most common cause of COPD in the United States. Long-term smoking or exposure to breathing in tobacco smoke or pollutants in the air damages the lungs and airways.

In healthy lungs, the air that is breathed in travels down bronchial tubes, which often branch many times into thousands of smaller, thinner tubes called bronchioles. These tubes end in bunches of tiny round air sacs called alveoli, which are elastic or stretchy.

In COPD, less air flows in and out of the airways because of one or more reasons:

• The airways and air sacs lose their elastic quality.
• The walls between many of the air sacs are destroyed.
• The walls of the airways become thick and inflamed.
• The airways make more mucus than usual and can become clogged.

The following may raise your risk of COPD:

• Smoking: This is the main risk factor for COPD. Most people who have COPD smoke or used to smoke. People who have a family history of COPD are more likely to develop the disease if they smoke.
• Other lung irritants: These may include long-term exposure to air pollution, chemical fumes and dust from the environment or workplace, smoke from home cooking and heating fuels without ventilation, and secondhand smoke, which is smoke in the air from other people smoking.,
• Changes to lung growth and development: Diseases affecting the lungs when a baby is still in the uterus or during childhood can increase the risk.
• Infections: Conditions such as HIV and tuberculosis can raise your risk.
• Age: Your age may play a role in COPD risk if you have other risk factors, such as smoking. Most people who have COPD are at least 40 years old when symptoms begin.
• A condition that runs in families, called alpha-1 antitrypsin (AAT) deficiency: If you are born with this condition, smoking or long-term exposure to fumes or dust can lead to lung damage and COPD. AAT deficiency can also raise your risk for developing COPD at a younger age. Other potential genetic risk factors include vitamin D deficiency, and mutations in CHRNA genes.
• Asthma: About 1 in 5 people who have COPD also have asthma, a lung disease that causes swelling and narrows the airways.

Fact sheet

COPD Learn More Breath Better: Are You at Risk?

Learn more about the risk factors for COPD.

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COPD affects both men and women. However, COPD may affect women and men differently.

• Compared with older men, older women may be more likely to experience serious symptoms of COPD, such as severe shortness of breath, even if they smoke less during their lifetime than men.
• Women who have COPD are more likely to have symptoms at younger ages and be hospitalized for symptoms than men who have COPD.
• Women who have COPD tend to smoke less and have a lower body mass index (BMI) than men who have COPD.

The reason for the differences in COPD between men and women is not known. Researchers think the cause may be related to hormones or other physiological differences, or differences in biology, between men and women. Women have smaller lungs than men do, which also may render women’s airways more prone to narrowing upon irritant exposures than men’s airways are.