Chronic bronchitis is a condition that causes inflammation of the airways in the lungs and lasts for a long period of time. Many people have had experience with acute bronchitis that develops from a cold or other upper respiratory infection, but the chronic form of this disease is more severe. It is marked by excessive production of thick mucus in the airways that makes breathing and gas exchange difficult. Along with emphysema, chronic bronchitis is one of the two main forms of chronic obstructive pulmonary disease (COPD), which, according to the Mayo Clinic, is a leading cause of death worldwide. There are several causes of chronic bronchitis.
Smoking
According to the Mayo Clinic, cigarette smoking is the number one cause of COPD and chronic bronchitis specifically, and PDRhealth.com reports that it causes 80 to 90 percent of all cases of the disease. The lining of the airways and the lungs is covered with small hairlike structures called cilia. These cilia are responsible for blocking and removing germs and other irritants from the lungs. Chemicals in tobacco smoke paralyze the cilia and eventually destroy them, allowing damage to and chronic irritation of the air passages. Cigarette smoke further irritates these delicate airways and causes them to become swollen and constricted, and sets off an inflammatory reaction that leads to mucus production. The more one smokes, the more often these airways and cilia are irritated, and eventually irreversible damage occurs. As the lungs fill with mucus, the small air sacs, called alveoli, are damaged. Since this is where gas exchange occurs, a person suffering with chronic bronchitis experiences shortness of breath with even minor activity.
Dust
Long-term exposure to dust of varying kinds can cause some of the same chronic irritation that cigarette smoke does. Over time, the dust overwhelms the cilia in the airways; they are unable to maintain the cleanliness required, and inflammation occurs. The inflammatory reaction within the lungs from any irritant causes the mucus production and damage that lead to breathing difficulty. Once an individual has developed chronic bronchitis, he may experience additional frequent respiratory infections, poor oxygen saturation and eventually heart failure, according to the University of Virginia Health System.
Chemical Fumes
An individual who is exposed to irritating chemical fumes for long periods of time can also develop chronic bronchitis. The condition can be difficult to treat, and the damage is often permanent.
Pollution
Living in an area where air pollution is consistently high can have the same effect on the lungs and airways as any of these other irritants do, and chronic bronchitis may result. Someone with a susceptibility to upper respiratory infections should not be exposed to high levels of pollution on a regular basis.
