Abstract
Concern over enhanced toxicity of air pollutant mixtures has led to the experimental demonstration that hydrogen peroxide (H2 O2 in concentrations of a few ppm killed animals after a brief exposure when inhaled with a nonlethal concentration (1 ppm) of ozone (O3). It was possible also to demonstrate a moderate degree of protection against otherwise lethal doses of H202, by a single prior exposure to H2O2. Moreover, cross tolerance against the organic peroxide, cumene hydroperoxide was afforded also by a prior exposure to H202. Particularly noteworthy, was a tolerance produced by a prior exposure to O3 to mixtures of H202 and O3, despite the fact that such mixtures normally show enhanced toxicity.