This is bronchitis. Many people suffer a brief attack of acute bronchitis with cough and mucus production when they have severe colds. Acute bronchitis is usually not associated with fever. Chronic bronchitis is defined by the presence of a mucus-producing cough most days of the month, three months of a year for two successive years without other underlying disease to explain the cough. It may precede or accompany pulmonary emphysema.
Cigarette smoking is by far the most common cause of chronic bronchitis.
The bronchial tubes of people with chronic bronchitis may also have been irritated initially by bacterial or viral infections. Air pollution and industrial dusts are also causes. Once the bronchial tubes have been irritated over a long period of time, excessive mucus is produced constantly, the lining of the bronchial tubes becomes thickened, an irritating cough develops, air flow may be hampered, and the lungs are endangered. The bronchial tubes then make an ideal breeding place for infections. Chronic bronchitis is estimated to affect 5 percent of the population of the United States.