A method and apparatus for aerating a region exposed to a gaseous/vaporous sterilant. A catalytic destroyer and a reactive chemical unit are used to reduce the concentration of the gaseous/vaporous sterilant within the region. The reactive chemical unit includes a chemistry that is chemically reactive with the gaseous/vaporous sterilant. In one embodiment, the gaseous/vaporous sterilant is vaporized hydrogen peroxide and the chemistry of the reactive chemical unit includes thiosulfate and iodide.