Prof Dr Med Clemens Bulitta, Ostbayerische Technische Hochschule

More and more evidence indicates that SARS-CoV-2 is transmitted via aerosols and accumulates over time indoors. Meanwhile also the WHO acknowledges the route of airborne transmission via aerosols in crowded and poorly ventilated spaces. Moreover, a recent study has detected viable SARS-CoV-2 virus in air samples of patient rooms collected 2 to 4.8m away from the patients providing further evidence for the importance of this route of transmission. Similar data is also available for other infectious agents like influenza virus. But this conclusion did not come easy as it has been a matter of controversial discussions for decades. The dominant opinion has been a transmission route via larger droplets, or through contaminated surfaces or people’s hands. Therefore, when SARS-CoV-2 emerged the assumption was that airborne transmission is also not really relevant. However, we now know better! Because of this aerosol-based transmission physical distancing and masks may not be sufficient to prevent SARS-CoV-2 transmission as well as other airborne infectious diseases in indoor settings.

Comprehensive air and ventilation management seem to be imperative to cope with the COVID-19 pandemic as well as airborne infection transmission. Thus, there clearly is a need to come up with innovative concepts and solutions for air management and ventilation. This is especially important for health care facilities, i.e. hospitals and nursing homes but also for public places like i.e. shops, offices, day care, schools, restaurants, public transport etc. It seems critical to optimize ventilation practices and consider (technical) ventilation systems. All stakeholders especially authorities, HVAC manufacturers and building engineers should have a focus on airflow optimization through i.e. changes to existing ventilation systems, air-purification and decontamination technologies as well as airflow management. Of course we could also learn from established and effective (technical) ventilation systems for operating theatres like i.e. the Opragon system.

The physics and the thermodynamics are the same and adaption of these systems to the needs and requirements of other indoor settings offers great potential for mitigating the risk of airborne infection transmission. This could help to avoid further “explosion” of the COVID-19 pandemic in fall and winter and allow to return to “normal” behavior in the above mentioned indoor spaces. Nevertheless, further research and studies are required to develop cost efficient and effective proven systems for such a broad range of applications.

The key role of indoor air management and ventilation systems for the prevention of transmission of COVID-19 as well as other infections

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