Abstract
Mice exposed to 1.5 ppm ozone for four hours per day, five days per week for two months exhibited no pathology of the lungs. Other mice, similarly exposed, exhibited no increased susceptibility to intravenously administered Mycobacterium tuberculosis nor to BCG vaccine. Exposure of mice to 1.5 ppm ozone for two hours per day for nine to twelve months increased incidence of fatal natural pulmonary infection. The acute four hour ED50 of ozone for producing pulmonary edema was 3.66 ppm.