Airborne disinfection (AD) using vaporized hydrogen peroxide (VH₂O₂) demonstrates documented microbiological efficacy against a broad spectrum of microorganisms. Bacteria, viruses, spores and fungi: this process provides a validated technical solution for environments where the elimination of pathogens must be complete, traceable and compliant with regulatory requirements.
Which microorganisms are targeted by airborne disinfection?
VH₂O₂ used in airborne disinfection provides a broad biocidal spectrum. Its mode of action relies on the production of oxidative free radicals that destroy essential cellular components of microorganisms, including membranes, proteins and nucleic acids. This mechanism acts against all microbiological categories targeted in controlled environments.
Vegetative bacteria
Airborne disinfection using VH₂O₂ eliminates vegetative bacteria, including multidrug-resistant species. Targeted microorganisms include:
- Methicillin-resistant Staphylococcus aureus (MRSA)
- Clostridium difficile (vegetative form)
- Pseudomonas aeruginosa
- Escherichia coli
- Listeria monocytogenes
- Salmonella spp.
These bacteria are responsible for healthcare-associated infections and industrial contamination. Airborne disinfection enables their inactivation on all treated surfaces, including areas inaccessible to manual cleaning.
Bacterial spores
Bacterial spores are among the most resistant microorganisms to biocidal agents. Their protective structure gives them resistance to conventional disinfectants, heat and many chemical processes. Airborne disinfection using VH₂O₂ is one of the few processes capable of demonstrating validated sporicidal activity at log-6 levels.
Geobacillus stearothermophilus and Bacillus subtilis spores are used as reference biological indicators to validate airborne disinfection cycles. Their complete inactivation demonstrates the maximum effectiveness of the process.
Viruses
Airborne disinfection demonstrates virucidal efficacy against a broad spectrum of enveloped and non-enveloped viruses:
- Influenza virus
- Coronaviruses, including SARS-CoV-2
- Adenoviruses
- Noroviruses
- Hepatitis B and C viruses
VH₂O₂ degrades the surface proteins of enveloped viruses and alters the genome of non-enveloped viruses, resulting in their inactivation on treated surfaces.
Fungi and molds
Filamentous fungi and yeasts are also sensitive to airborne disinfection. Aspergillus niger, frequently used as an indicator of fungal resistance, is among the microorganisms targeted during validation testing. Airborne disinfection treats fungal contamination in pharmaceutical production areas, cleanrooms and storage spaces.
What is log-6 reduction and why is it critical ?
A log-6 reduction corresponds to a 99.9999% reduction of the initial microbial population. It represents the decontamination level required in highly critical environments such as sterile areas, pharmaceutical isolators and containment laboratories.
Solidfog’s VH₂O₂ airborne disinfection is one of the few processes capable of achieving this level of performance in a reproducible and documented manner. This capability differentiates airborne disinfection from conventional surface disinfection methods, which are generally limited to reductions ranging from log-3 to log-4.
The log-6 reduction is validated using biological indicators placed at the most critical points within the treated space. These indicators contain a known concentration of resistant bacterial spores. Their complete inactivation after the cycle validates the effectiveness of the process throughout the entire volume.
Factors affecting the effectiveness of airborne disinfection
The microbiological effectiveness of airborne disinfection does not depend solely on VH₂O₂ concentration. Several physical and environmental parameters directly influence cycle performance.
Hydrogen peroxide concentration
The concentration of H₂O₂ within the treated space plays an important role in the effectiveness of the biodecontamination cycle. It must be controlled and properly adjusted, as a higher concentration does not necessarily guarantee a better sporicidal effect. SolidFog systems monitor this parameter in real time to ensure reliable and reproducible cycles.
Relative humidity
Relative humidity plays a key role in the effectiveness of VH₂O₂. An appropriate humidity level promotes the deposition of microdroplets on surfaces and improves contact between the biocide and target microorganisms. Humidity levels that are too low or too high compromise decontamination homogeneity.
Microdroplet size
The particle size generated by the atomizer determines distribution throughout the treated volume. Controlled microdroplet sizes ensure penetration into complex areas such as equipment corners or spaces beneath work surfaces.
Contact time
The duration of surface exposure to VH₂O₂ determines the level of microbiological reduction achieved. This parameter is defined during cycle development according to the volume, geometry of the space and required decontamination level.
Distribution homogeneity
Homogeneous distribution of the biocide throughout the treated volume determines the overall effectiveness of the cycle. The number and positioning of injection points are studied beforehand to ensure that every area receives a sufficient biocidal dose.
Validation of effectiveness: a key regulatory requirement
In pharmaceutical, healthcare and research sectors, the effectiveness of an airborne disinfection cycle must be validated according to documented protocols. This validation relies on two complementary types of indicators.
Biological indicators
Biological indicators contain a known population of resistant spores. Their strategic placement within the treated space makes it possible to verify that the cycle achieves the required microbiological reduction at every critical point. Their complete inactivation constitutes proof of process effectiveness.
Chemical indicators
Chemical indicators make it possible to monitor VH₂O₂ concentration during the cycle. They complement biological indicator data and provide continuous traceability of process parameters in accordance with 21 CFR Part 11 requirements and GMP standards.
EN 17272:2020 makes it possible to evaluate the performance of an automated airborne disinfection process using a given biocide under defined test conditions. It is a recognized reference for demonstrating the effectiveness of a technology, but it does not replace the specific validation of a biodecontamination cycle in its actual environment of use.
Airborne disinfection compared with other decontamination methods
Airborne disinfection stands out from alternative methods through its ability to treat entire volumes in an automated and validatable manner.
Manual disinfection is limited to accessible surfaces and produces results that vary depending on the operator. It generally achieves microbiological reductions ranging from log-3 to log-4, which are insufficient for highly critical environments.
UV-C radiation provides limited effectiveness restricted to surfaces directly exposed to the light source. Areas in shadow or beneath equipment do not receive a sufficient dose, compromising treatment homogeneity.
Formaldehyde fumigation can achieve high microbiological reduction levels, but its use is now heavily regulated due to its carcinogenic nature and the associated risks for operators.
VH₂O₂ airborne disinfection combines a broad biocidal spectrum, log-6 microbiological reduction, absence of toxic residues after aeration and documented validation capabilities. These characteristics make it the reference process for environments where contamination control is a regulatory requirement.
Solidfog Technologies: validated and documented airborne disinfection cycles
Solidfog develops airborne disinfection systems whose effectiveness is validated using biological and chemical indicators, in accordance with EN 17272:2020 and GMP requirements. Each cycle generates traceable and auditable data compliant with the strictest regulatory standards.