While bronchitis itself may be caused by one-time exposure to bacteria or a virus, chronic bronchitis is the result of long-term irritation of the respiratory tract. Cigarette smoking is the most common of all causes of chronic bronchitis. In the same vein, frequent, long-term exposure to secondhand smoke may also result in the disease. Further causes of chronic bronchitis include regular inhalation of other irritants that may result from the workplace, such as dust or chemical pollutants. Although rarer, those who have acid reflux disease may also be at risk of contracting chronic bronchitis.
Cigarette smoking is the main cause of chronic bronchitis because of the constant exposure of tobacco smoke to the lungs. When the lining of the bronchioles are irritated to a certain extent, the tiny hairs in the lining that normally trap pollutants, known as cilia, shut down and stop functioning. This causes even further clogging and irritation, and in response to their shutting down, the body secretes an excess amount of mucus. Consistent exposure to tobacco smoke is almost guaranteed to keep the bronchioles in this cycle. Secondhand smoke can work the same way, and those that are constantly exposed to it may be at a similar risk of contracting chronic bronchitis as smokers themselves.
Regular inhalation of dust can also lead to chronic bronchitis. The bronchitis may manifest as a result of a condition called pneumoconiosis, a restrictive lung disease that is most associated with those whose occupation forces them to be continually exposed to dust. The disease can vary depending on the kind of dust one is being exposed to. Coal, carbon, and asbestos may all be causes of chronic bronchitis depending on the occupation of the person.
A variety of chemical pollutants can become further causes of chronic bronchitis given repeated exposure. Airborne substances such as ammonia, chlorine, hydrogen sulfide, and sulfur dioxide are especially likely to put a person at risk. Workers who are prone to being exposed to these pollutants should make use of masks and other precautionary attire to reduce the risk of contracting the infection.
Untreated acid reflux disease can sometimes lead to chronic bronchitis. The esophagus of individuals who have this disease can often be irritated by the stomach acids that travel upwards into that area. This can lead to inhalation of the person's gastric contents, which may cause irritation of the airways. There are many treatments available for acid reflux disease, making chronic bronchitis under these circumstances a generally rare occurrence, but untreated cases put patients at a higher risk of long-term inhalation of their own stomach acids.