Abstract
Quantitative measurements of respiratory function of guinea pigs were made before, during, and after exposure to low concentrations of ozone, and nitrogen dioxide. The earliest effects detected during exposure to either of the gases were increased respiratory frequency and decreased tidal volume. These effects were noted during 2-hour exposures to concentrations of O3 as low as 0.34 ppm or within 4 hours of exposure to NO2 at a concentration of 5.2 ppm. Previous exposure to O3 did not result in tolerance to the respiratory function changes produced during exposure to a 1.5-ppm concentration of the gas. Voluntary running activity of mice was depressed during exposure to concentrations of O3 between 0.2 and 0.7 ppm and to NO2 concentrations of 7.7 to 20.9 ppm.