Short-term effects of cigarette smoking on bronchial clearance in humans.

The short-term effects of cigarette smoking on the bronchial clearance of inhaled monodisperse radioactive insoluble particles was studied in nine nonsmokers and six smokers. Each subject inhaled two aerosols of the same particle size, tagged with a different isotope, with an interval of several hours between aerosol exposures. Simultaneous measurements were made of the clearance of both aerosols. Smoking of from two to seven cigarettes was started shortly after the second tagged aerosol. Comparison of the bronchial clearance times of the two tagged aerosols gave a minimum estimate of a twofold transient speedup in deep bronchial clearance caused by the cigarette smoking in both smokers and nonsmokers.