Bronchitis is an inflammation of the bronchial (pronounced -brawn-kee-ull) tubes, or bronchi. Bronchial tubes are the air passages that extend from the windpipe into the lungs.
Some of the most common symptoms are: a cough, wheezing, fever, and soreness in the chest.
Bronchitis is contagious and can be spread by direct or indirect contact. Bronchitis may be caused by a virus, bacteria, smoking or the inhalation of chemical pollutants or dust. When the cells of the bronchial-lining tissue are irritated beyond a certain point, the tiny hairs (cilia) within them, which normally trap and eliminate pollutants, stop functioning. Consequently, the air passages become clogged by debris and irritation increases. In response, a heavy secretion of mucus develops, which causes the characteristic cough of bronchitis. The most common cause of acute bronchitis is a viral infection such as the flu. Sometimes bacteria can cause this disease as well. Breathing air that contains irritants, such as chemical fumes, acid fumes, dust or smoke, increases the risk of the disease.