Smoking is a principal risk factor for the development of chronic obstructive pulmonary diseases (COPD) and chronic obstructive bronchitis (COB). The occurrence of COB is in direct relation with the usage of cigarettes, while its severity depends upon the number of cigarettes smoked. The COB-associated mortality rate has no trend towards lowering. Cigarette smoke impairs bronchial mucosa, facilitates the development of bronchopulmonary bacterial infection because of declining local immunity. There is also a strong relation between chronic obstruction of the respiratory tract, bronchial hyperactivity and smoking.
