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Tracheobronchial clearance was studied with a test aerosol of 6μm monodisperse particles of fluorinated ethylene propylene (Teflon 120), tagged with 99m Tc, produced by a spinning disc technique. External measurements of the radioactivity in the lungs determined the rate of clearance. Seventeen smokers were studied while they were smokers, one week after they had stopped smoking, and about three months after cessation. Their clearance on the average was faster three months after they had stopped smoking but nearly unchanged one week after they had stopped.
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Camner et al. (1973) studied this question.
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