The "natural history" of COPDby which we mean the progression of physical damage and its impact on the patientdepends on whether bronchitis or emphysema predominates.

The typical patient with chronic bronchitis predominating first visits his doctor because he has been unable to shake a bad cold that has "settled in my chest." It is the first or second time that he has been steadily coughing up large quantities of mucus for several months after getting a cold. He is usually between 40 and 55 years old and a heavy smoker, and more often male than female (although these odds are changing).

Although the patient has just become aware of his symptoms, the disease has been silently progressing for several decades. During this time his airways have been continuously assaulted by the harmful substances inhaled in his cigarette smoke. These substances have inflamed his airways, gradually increased mucus production throughout his airways, and eventually damaged the ability of his ciliated epithelial cells to move mucus out of his smaller airways. His coughstill moderately effectivenow has to work hard to keep up with the pace of mucus production in his larger airways. In addition to inhaled cigarette smoke, any other air pollutants in his