Deposition of 2- and 7-mu m particles in the rabbit lung.

Depostion of 2- and 7-mu m polystyrene particles tagged with scandium-46 and gold-198, respectively, was studied in 6 rabbits. Deposition was estimated in the 3 major bronchi and their extensions in the right lung by dissecting free the bronchial tree and measuring the radioactivity in the various sections. The rabbits were exposed to a mixture of 2- and 7-mu m polystyrene particles. The particle content among bronchi was highest in the lower lobe and lowest in the upper lobe. The average particle content per unit of bronchial surface did not differ among the bronchi or among different locations in the lobe bronchus and its extension. The ratio of 7- to 2-mu m particles was greater in all bronchial sections than in the whole lung.