[en] The effect of ⁹⁰Y inhaled in fused clay particles on the pulmonary clearance of inhaled Staphylococcus aurcus in mice was investigated to provide an improved understanding of the influence of localized irradiation from inhaled radionuclides on infectious processes. Pulmonary clearance of inhaled S. aurcus was suppressed in mice with initial lung burdens of 20 μCi ⁹⁰Y or greater at 2, 3, and 4 weeks after inhalation exposure to ⁹⁰Y. Suppressed clearance rates were accompanied by radiation-induced lifespan shortening, retarded increases in average body wieght, suppression of blood lymphocyte count, and pulmonary lesions. Only equivocal suppression of bacterial clearance was observed in mice with initial lung burdens of less than 20 μCi ⁹⁰Y that were tested from 1 through 52 weeks after inhalation exposure. An initial lung burden of 1 μCi ⁹⁰Y was estimated to result in 400 rad to the lung delivered within 24 days after exposure