Development and evaluation of a test standard for the effectiveness of air purifiers in reducing the viral load in indoor air

Project start / November 01, 2021

The Corona pandemic has demonstrated the importance of protecting people against infection through airborne pathogens in indoor environments. Air-purification systems can significantly contribute towards this. Currently, however, there is no uniform procedure for testing their effectiveness. We are developing a possible test standard in order to close this gap. In the future, this should facilitate the health evaluation of workplaces with regard to viruses and other airborne pathogens.

Last modified: November 01, 2021

The photo shows an office with three computer workstations, each with one person sitting and working. Corona viruses are "floating" in the air (graphic visualization). — © Shutterstock / Fraunhofer WKI
In offices and other indoor areas, aerosols containing infectious virus particles such as SARS-CoV-2 can accumulate and spread in the air - particularly if the ventilation possibilities are poor. Air purifiers can counteract this.

The transmission of respiratory-associated viruses such as SARS-CoV-2 occurs primarily via the inhalation of particles containing the virus. These belong to the group of bioaerosols. Bioaerosols are all accumulations of particles in the airspace to which fungi, bacteria, viruses and/or pollen, as well as their cell-wall constituents and metabolic products, adhere.

In order to reduce the viral load in the bioaerosol, air purifiers employ various procedures that can be divided into two classes:

Reduction of the virus particle concentration through e.g.

Filtering
Electrostatic precipitation

Inactivation of the viruses through e.g.

UV irradiation
Ozonization
Ionization / Plasma generation

Depending on the air-purification method, emissions may occur that are critical to health, including (UV) radiation; secondary reaction products such as nitrogen oxides or ozone; noise; and air currents. The test report should therefore consider not only the effectiveness in reducing the pathogen load but also possible health risks that may arise as a result of the operation of the air purifier.

The primary task of the Fraunhofer WKI in this project is the establishment and optimization of a bioaerosol test chamber. On the basis of market research, we select commercially available air purifiers for each device type, install them in the chamber and then perform measurements. From this, we are able to develop a standardized mode of operation of the test chamber for air purifiers.

In addition, we are also working together with the Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour (ITTN) at the University of Veterinary Medicine Hannover on the following project elements:

Identification of a suitable test bioaerosol and definition of rules for standardized production
Development of a measurement procedure for the recovery of aerosolized viruses and determination of virus reduction during and after utilization of the air purifiers
Development of a comprehensive test protocol and renewed testing under practical conditions
Proposal for a standardized testing procedure including consideration of possible health hazards due to chemical reaction products and UV radiation

Scientific studies of COVID-19 infections yield the following picture: Infections primarily occur in indoor environments. The risk of (mass) infections in indoor areas depends substantially on the indoor-air treatment.

Workplaces, educational institutions, and places of assembly should be designed in the long term to provide better protection against infection through airborne viruses – such as the SARS-CoV-2 virus – for all people who spend time indoors with other people. Air-purification systems hereby play a decisive role.

With the development of a uniform testing procedure for air purifiers, we are providing a significant contribution towards ensuring that the devices can be used efficiently and safely. This can save lives and reduce overheads.

Economic advantages

A testing standard for air purifiers would simplify the health evaluation and equipping of workplaces with respect to viruses and other airborne pathogens. This would also help insurance companies and employers.

Manufacturers and installers of air-purification systems could prove the effectiveness of their devices to customers.

When the effectiveness of a device is known and can be compared with uniformly tested devices, the planning options for the acquisition as well as the retrofitting of stock air-purification systems can be improved. This can benefit diverse businesses, including architects/building designers, developers, employers, educational institutions, sports clubs and event organizers.

Project partners

Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour (ITTN) at the University of Veterinary Medicine Hannover, Foundation

The ITTN has been addressing animal and environmental hygiene for more than 40 years. One research focus is the investigation and evaluation of air quality in animal pens and sties, in the environment and in production areas, as well as the estimation of the effects of air pollution on animals, humans and the environment. The institute is supporting the project through its expertise and technical equipment on the topic of bioaerosols and airborne zoonotic agents.

Funding

Official project title:
Entwicklung und Evaluierung eines Prüfstandards für die Wirksamkeit von Luftreinigern zur Reduktion der Virenfracht in Innenraumluft – Teilvorhaben 1: Bioaerosol-Prüfkammer
(Development and evaluation of a test standard for the effectiveness of air purifiers in reducing the viral load in indoor air – Sub-project 1: Bioaerosol test chamber)

Funding body:
Deutsche Gesetzliche Unfallversicherung e. V. (German Social Accident Insurance, DGUV)

Duration:
1.11.2021 to 31.10.2023

Research project

Development and evaluation of a test standard for the effectiveness of air purifiers in reducing the viral load in indoor air

Economic advantages

Project partners

Funding

Contact Press / Media

Dr. Annette Clauß

Development and evaluation of a test standard for the effectiveness of air purifiers in reducing the viral load in indoor air

Social relevance

Economic advantages

Project partners

Funding