Inflammation of the bronchi (air passages of the lungs consisting of muscle tissue lined with mucous membranes). 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. Additional Info: Bronchitis can be acute or chronic. Acute bronchitis is a short-term condition that usually resolves itself and is not uncommon after a cold or single exposure to arespiratory irritant. Chronic bronchitis is one of three forms of chronic obstructive pulmonary disease (COPD), the other two being emphysema and and certain forms ofasthma. Chronic bronchitis is usually associated with smoking. Certain occupations that involve irritating dust or fumes put workers at higher risk. The American Lung Association lists coal miners, grain handlers, metal molders, and other workers exposed to dust as being at a higher risk for chronic bronchitis. Workers in such professions should use appropriate protective measures such as respirators and they should avoid tobacco smoke. See also: Asthma, Emphysema, Respiratory