COPD is most often caused by smoking as the tobacco smoke destroys fibers in the lungs and irritates the airways, explains WebMD. COPD may also be caused by environmental factors such as breathing in dust, pollution or chemical fumes over long periods of time. Chronic bronchitis occurs when these irritants cause the bronchial tubes to become inflamed and secrete a lot of mucus, which inhibits the airways. Emphysema occurs when air sacs around the lungs that normally expand and contract during breathing become damaged and lose their stretch, decreasing their ability to carry air in and out of the lungs.
COPD is most common in those over the age of 60, though younger people with histories of serious lung infections also contract the disease, according to WebMD. COPD progresses over time, and damage to the lungs caused by its underlying diseases cannot be reversed. People can slow the progression of COPD by quitting smoking, avoiding exposure to pollutants and taking medications prescribed by their doctors. In more serious cases of COPD, patients receive oxygen treatments at home or in the hospital.