Comparative Decomposition. of Ozone in the Nasopharynx of Beagles

Abstract

The mean tracheal concentration of ozone (O₃) was measured in two groups of physiologically unaltered beagles. One group had been exposed to 0₃ for 18 months and consisted of four subgroups exposed to the following daily concentration × time regimens: 1 ppm × 8 hours, 2 ppm × 8 hours, 3 ppm × 8 hours, and 1 ppm × 24 hours. The control group consisted of previously unexposed beagles sampled similarly at either 1 ppm O₃ or 3 ppm O₃ following one hour of acclimatization. For groups receiving equal O₃ concentrations, the chronically exposed subjects had statistically higher mean tracheal concentrations of O₃. All dogs inspiring higher concentrations of O₃ demonstrated significantly higher mean tracheal concentrations. Furthermore, the subgroup chronically exposed to 1 ppm × 24 hours had statistically higher mean tracheal concentrations than the chronically exposed subgroup receiving 1 ppm × 8 hours.