**2.2 Dry hydrogen peroxide and photocatalytic oxidation**

Both DHP and Photocatalytic Oxidation (PCO) technologies utilize photocatalysis during their respective processes, however DHP devices are not PCO devices [18, 23]. DHP technology uses a plasma-separation process to specifically produce free H2O2. Photocatalytic Oxidation technology, however, rapidly consumes any H2O2 that may form in the plasma, because H2O2 has a highly positive reduction potential (0.71 eV) and will be immediately reduced to water by subatomic particles in the plasma [24]. Photocatalytic Oxidation devices rely on a dense internal plasma zone within the device, but the microbicidal properties of the plasma only affect airborne microbes that circulate through the device, unless the device also produces ozone, which would impact microbes outside of the device.
