The Facts
Chronic bronchitis belongs to a larger family of medical conditions known as chronic obstructive pulmonary disease (COPD). The term COPD is given to any condition that causes difficulty in breathing as a result of constant blocking of the airways.
Bronchitis is said to occur when the airways in the lungs (bronchial tubes) become partly clogged with large amounts of mucus and become narrowed due to inflammation and swelling. These symptoms typically result in a chronic cough. When cough and sputum have been present for more than three months in each of two consecutive years, the condition is called chronic bronchitis. In North America, about 1 in 20 people suffers from chronic bronchitis. Smoking for many years causes about 90% of chronic bronchitis cases, and thus the great majority of people with chronic bronchitis are over 45 years of age. The risk of chronic bronchitis is also increased in workers employed in certain occupations such as coal mining, welding, asbestos work, or grain handling.
When breathing suddenly becomes more difficult for a person with chronic bronchitis, he or she may be experiencing an acute exacerbation of chronic bronchitis (AECB). During an acute exacerbation, breathing becomes much more difficult because of further narrowing of the airways and secretion of large amounts of mucus that is often thicker than usual.
Causes
The further narrowing of airways in people with chronic bronchitis that results in AECB can be caused by allergens (e.g., pollens, wood or cigarette smoke, pollution), toxins (a variety of different chemicals), or acute viral or bacterial infections. This is because the extra mucus in the airways of a person with chronic bronchitis provides a good place for viruses and bacteria to grow. Bacterial infections are usually associated with mucus that turns a yellow or greenish color and is typically much thicker than usual. Colored mucus does not necessarily mean the person has a bacterial infection, however.
