Ozone and Nitrogen Dioxide Exposure

Abstract

Since ozone and nitrogen dioxide impair pulmonary resistance to infection by inhibiting the function of the alveolar macrophage, we investigated the effect of combinations of these gases to determine if they interacted biologically in a synergetic, indifferent, or antagonistic manner. Mice were exposed to atmospheres of ozone and nitrogen dioxide for 17 hours prior to, or four hours after, infection with aerosols of Staphylococcus aureus labeled with radioactive phosphorus (³²P). Animals infected and then exposed to various oxidant combinations manifested bactericidal dysfunction only when the level of one of the pollutants approximated its individual threshold value. Similar results were obtained when mice were exposed to pollutants for 17 hours before infection. Hence, the pulmonary consequence of exposure to ozone and nitrogen dioxide is equivalent to the injury that would be expected from each individual oxidant.