People with COPD often have chronic bronchitis, and the primary cause of chronic bronchitis is smoking cigarettes. Chronic bronchitis is characterized by a chronic cough and chronic mucus production without another known cause (such as infection).
Cells that line the airways in the lungs normally produce mucus as part of the body's defense mechanism against bacteria, viruses, and other foreign particles. The mucus traps these particles, and tiny hair-like projections in the airways (called cilia) sweep the dirty mucus up and out of the lungs.
In chronic bronchitis, more mucus than normal is constantly produced. This causes a build-up of excess mucus that the cilia are unable to clear from the lungs. Exacerbating this is the fact that the cilia become dysfunctional and are less efficient at expelling mucus from the lungs. The build-up of mucus narrows the airways and provides havens for bacteria to thrive leading to more frequent and serious lung infections, and even more mucus production.
The hallmark symptoms of chronic bronchitis are:
Shortness of breath.