Mailings of envelopes containing anthrax spores (Bacillus anthracis) have caused serious disruptions of business operations in various parts of the United States, and several people tragically have lost their lives from resulting exposure to anthrax. These incidents have caused U.S. government agencies to investigate this material and to evaluate methods of neutralizing it. Ozone is one candidate countermeasure.In this paper, what is known about ozone and its ability to destroy B. anthracis spores (and accepted surrogates) is discussed. High relative humidity is required to “soften up” the spore coating prior to addition of any disinfectant. Ozone clearly is a sufficiently powerful oxidant to destroy B. anthracis in relatively short exposure times.