Aerosol-based disinfection protocol for aircraft: a solution for the conflict between material compatibility and...

Every year, billions of passengers, pets, and livestock are transported by air, which increases the risk of a global spread of pathogens like severe acute respiratory syndrome coronavirus 1 and 2, H1N1 influenza, the Ebola virus, and foot-and-mouth disease virus. However, due to its complexity and high safety standards, aircraft decontamination is limited to manual surface disinfection, and an approved method for disinfecting otherwise inaccessible areas is still unavailable. To address this issue, we present the development and validation of an effective room disinfection method utilizing low concentrations of aerosolized peroxyacetic acid (aPAA), stabilized by hydrogen peroxide, known as "dry fog." Therefore, we determined the minimal effective antimicrobial concentration of aPAA for a wide range of agents, including bacteria, viruses, and bacterial endospores. Then, we applied the developed disinfection protocol to a large panel of relevant materials multiple times in the context of the official material compatibility tests (MCTs) requested by the European Union Aviation Safety Agency (EASA) to demonstrate that its application will not cause a negative effect on the aircraft airworthiness. After successfully passing these complex material compatibility tests, we finally validated the disinfection protocol within a narrow-body aircraft A320 for its antimicrobial efficacy by using the most resistant microorganisms to aPAA among our test organisms, the bacteriophage MS2, and spores of Geobacillus stearothermophilus. Thus, we are now able to present the first aerosol-based room disinfection method suitable for aircraft that could easily be adopted for other aircraft types and other means of mass transport as well.

Despite numerous outbreaks in recent years, particularly the Ebola virus epidemic and the severe acute respiratory syndrome coronavirus 2 pandemic, there is still no approved method for disinfecting contaminated aircraft. Due to the highly complex nature of aircraft material and technology, it is difficult to balance the antimicrobial efficacy and material compatibility of the biocides used in a way that meets high safety standards. Here, we demonstrate an aerosol-based disinfection protocol using a mixture of peracetic acid and hydrogen peroxide. This protocol passed all material compatibility tests according to relevant aircraft certification specifications established by the European Union Aviation Safety Agency, as well as the manufacturer qualification test programs, and proved to be highly effective against viruses, bacteria, and even bacterial endospores without compromising the airworthiness of the aircraft. By targeting both contaminated surfaces and objects, as well as airborne pathogen reservoirs, it minimizes the spillover risk of zoonotic agents and prevents the mechanical transmission of high-consequence agricultural pathogens into disease-free geographical regions. This makes it the first suitable semi-automatic airborne disinfection method that can be used in addition to routine manual surface disinfection following contamination resulting from contact with people, animals, or goods infected or contaminated with high-consequence pathogens.