Causes
In developed countries like the United States, the single biggest cause of COPD is cigarette smoking. About 90 percent of people who have COPD are smokers or former smokers.
Among long-time smokers, 20 to 30 percent develop COPD. Many others develop lung conditions or have reduced lung function.
Most people with COPD are at least 40 years old and have at least some history of smoking. The longer and more tobacco products you smoke, the greater your risk of COPD is. In addition to cigarette smoke, cigar smoke, pipe smoke, and secondhand smoke can cause COPD.
Your risk of COPD is even greater if you have asthma and smoke.
You can also develop COPD if you’re exposed to chemicals and fumes in the workplace. Long-term exposure to air pollution and inhaling dust can also cause COPD.
In developing countries, along with tobacco smoke, homes are often poorly ventilated, forcing families to breathe fumes from burning fuel used for cooking and heating.
There may be a genetic predisposition to developing COPD. Up to an estimated 5 percent Trusted Source of people with COPD has a deficiency in a protein called alpha-1-antitrypsin. This deficiency causes the lungs to deteriorate and also can affect the liver. There may be other associated genetic factors at play as well.
COPD isn’t contagious. [1]