Chronic bronchitis is a respiratory illness that makes it difficult to breathe, states the American Lung Association. Unlike acute bronchitis, chronic bronchitis is not associated with an underlying illness.
Someone with chronic bronchitis has a persistent mucus-producing cough, explains the American Lung Association. The cough must last for three months of the year, at least two years in a row, to be considered chronic. Constant irritation of the bronchial tubes causes reduced air flow, scarring of the lungs and excessive mucus production. The constant irritation also increases the risk for airway infections. Although smoking cigarettes is the most common reason to develop chronic bronchitis, people also develop the condition after having viral or bacterial infections.
Chronic bronchitis is a serious disease that often cannot be reversed, according to PDRhealth. As the condition worsens, air flow becomes more restricted, making it harder to breathe. Worsening chronic bronchitis also causes increased mucus production. In addition to smoking, exposure to chemicals that irritate the airway can also cause chronic bronchitis. Examples of respiratory irritants include ammonia, hydrogen sulfide and sulfur dioxide. Grain dust and coal dust also irritate the respiratory tract. Children who have repeated respiratory infections have a risk of developing chronic bronchitis in adulthood. This condition is classified as a type of chronic obstructive pulmonary disease.