Elevating the relative humidity within the environment being decontaminated has been shown to be important when targeting sporicidal reduction. Spores are hard-shelled, and the elevated humidity levels cause the spore walls to swell and crack. This allows the sterilant to penetrate the spore wall much quicker and easier, providing faster kill times for the decontamination process.
This has been demonstrated through the use of chlorine dioxide gas. Biological Indicators, consisting of over a million geobacillus stearothermophilus spores, were subjected to chlorine dioxide gas cycles at varying relative humidity levels and exposure dosages. Results are shown below, with greater dosages required at dryer conditions.