Airborne Disinfection by Dry Fogging Efficiently Inactivates Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Mycobacteria, and Bacterial Spores and Shows Limitations of Commercial Spore Carriers

Abstract

Airborne disinfection of high-containment facilities before maintenance or between animal studies is crucial. Commercial spore carriers (CSC) coated with 106 spores of Geobacillus stearothermophilus are often used to assess the efficacy of disinfection. We used quantitative carrier testing (QCT) procedures to compare the sensitivity of CSC with that of surrogates for non-enveloped and enveloped viruses including SARS-CoV-2, mycobacteria, and spores to an aerosolized mixture of peroxyacetic acid and hydrogen peroxide (aPAA/HP). We then used the QCT methodology to determine relevant process parameters to develop and validate effective disinfection protocols (≥ 4 log10 reduction) in various large and complex facilities. Our results demonstrate that aPAA/HP is a highly efficient procedure for airborne room disinfection. Relevant process parameters such as temperature and relative humidity can be wirelessly monitored. Furthermore, we found striking differences in inactivation efficacies against some of the tested microorganisms. Overall, we conclude that dry fogging a mixture of aPAA/HP is highly efficient against a broad range of microorganisms as well as material compatible with relevant concentrations. Furthermore, CSC are artificial bio-indicators with lower resistance and thus, should not be used for validating airborne disinfection when microorganisms other than viruses have to be inactivated. IMPORTANCE Airborne disinfection is not only of crucial importance for the safe operation of laboratories and animal rooms where infectious agents are handled, but can also be used in public health emergencies like the current SARS-CoV-2 pandemic. We show that dry fogging a mixture of aPAA/HP is highly microbicidal, efficient, fast, robust, environmentally neutral, and a suitable airborne disinfection method. In addition, the low concentration of dispersed disinfectant, particularly for enveloped viral pathogens like SARS-CoV-2, entails high material compatibility. For these reasons and due to the relative simplicity of the procedure, it is an ideal disinfection method for hospital wards, ambulances, public conveyances and indoor community areas. Thus, we conclude that this method is an excellent choice for control of the current SARS-CoV-2 pandemic.

A review of methods to reduce the probability of the airborne spread of COVID-19 in ventilation systems and enclosed spaces

“… The effects of filter loading have not been thoroughly investigated regarding the longevity of inactivation efficiency. Chemical Disinfectants ( Ogata and Shibata, 2008 ; Pyrgiotakis et al, 2014 ; Vaze et al, 2019 ; Schinköthe et al, 2020 ; Akamatsu et al, 2012 ; Occupational Safety and Health Administration, 2020 ) Very effective method with high inactivation rate. Dangerous if humans are exposed to or ingest any of the chemicals.…”

“…The dry fog may be delivered to a space and dispersed through the HVAC ventilation system to provide a readily available and convenient method of application. aPAA-HP has previously been tested using multiple viral and spore agents, including COVID-19 ( Schinköthe et al, 2020 ). The purpose of the cited study was to determine the protocols of using aPAA-HP necessary to effectively disinfect a facility, where it was demonstrated that dry fogging was highly effective.…”

“…Dry fogging has been tested as a critical disinfectant in medical facilities, but would likely be impractical in a common, everyday scenario such as a commercial or residential application. However, in the case of another pandemic or dangerous outbreak, it could be beneficial towards disinfecting areas of a workplace exposed by infected employees ( Schinköthe et al, 2020 ).…”

Treatment with dry hydrogen peroxide accelerates the decay of severe acute syndrome coronavirus-2 on non-porous hard surfaces

“…Our data are consistent with the previous reports that coronaviruses are relatively environmentally stable but are sensitive to vaporized hydrogen peroxide 8 . Dry fogging of hydrogen peroxide in the form of mixtures containing peroxyacetic acid and hydrogen peroxide has also been demonstrated to be effective in inactivating SARS-CoV-2 18 . In this study, the use of a commercially available portable device can provide a standardized and simplified decontamination procedure for contaminated surfaces containing SARS-CoV-2.…”

Dry-Fog-Dekontamination von mikrobiologischen Sicherheitswerkbänken nach Tätigkeiten mit SARS-CoV-2: Zyklusentwicklung und Prozessvalidierung für die Trockenvernebelung von Peroxyessigsäure

“…In addition to, and increasingly as a substitute for, formaldehyde fumigation and as an alternative to H 2 O 2 fumigation, the “dry fog” method is used for decontamination of rooms, including BSCs [ 7 ], [ 8 ], [ 9 ]. This method is based on the aerosolisation of disinfectants through the application of compressed air.…”