Divergences in the microbial inactivation pattern between vaporized hydrogen peroxide and aerosolised peracetic acid by dry fogging.

Abstract

In the present study, effective inactivation protocols were successfully developed and validated for the two airborne room disinfection methods vaporized hydrogen peroxide (VHP, H₂O₂) and dry fogging of aerosolized peroxyacetic acid (aPAA). Both methods were tested within the same HEPA filter housing (HEPA FH), allowing a direct comparison in an identical experimental setup. This approach provided a detailed comparison of their respective advantages and disadvantages. The main focus was on the determination of the microbicidal efficacy. This is the first time, that the efficacy of both methods has been clearly demonstrated for the most relevant classes of microorganisms using a broad spectrum of different test organisms. During the development phase of the respective optimal inactivation protocols the efficacy of the aPAA process was shown to correspond to the generally accepted microbicidal efficacy profile, whereas the efficacy pattern of the VHP process differed significantly from this. The VHP method demonstrated an exceptionally high sporicidal efficacy, significantly exceeding the measurable antiviral efficacy against both non-enveloped and even enveloped viruses. Moreover, even by reducing the used hydrogen peroxide (HP) amount drastically, no protocol could be applied in which the mycobacterial and the bacterial spore carriers were not be sufficiently inactivated. Based on these clear results, the current practice of using almost exclusively bacterial spore carriers for the establishment and validation of VHP-based inactivation protocols in particular have to be adjusted. Safe and effective inactivation protocols can only be developed by using suitable test organisms adapted to the respective individual requirements.