Cigarette smoking: objective evidence for lung damage in teen-agers.

High school students with 1 to 5 years' smoking experience have excessive cough, sputum production, and shortness of breath. When maximum expiratory flow is plotted against maximum expired volume, the curves of nonsmokers and smokers differ in shape. The smokers have lower flow rates at mid-vital capacity and at lower lung volumes. This probably reflects small airway obstruction in the smokers.