In the context of the European Aerosol Conference (EAC 2020), the local organizers from Gesellschaft für Aerosolforschung (GAeF) organized a scientific panel discussion on „Aerosols and COVID-19“. It took place in the evening of Thursday, September 3, at the 650-year old Coronation Hall in the Town Hall of Aachen, Germany. Due to the corona pandemic, it was the only in-person event during EAC 2020, which was otherwise held as a fully virtual conference from August 31 to September 4. EAC 2020 attracted 684 attendees from 44 countries to its online sessions and covered the whole range of European aerosol research and international collaborations.

For the panel discussion, the organizers were able to bring together an expert group largely consisting of GAeF members to discuss the latest state of knowledge regarding COVID-19 and aerosols:

Picture © Peter Hinschläger

Moderator Prof. Dr. Astrid Kiendler-Scharr Forschungszentrum Jülich GmbH
Mask testing Dr. Frank Drewnick Max Planck Institute for Chemistry Mainz
Aerosol measurement Prof. Dr. Otto Klemm University of Münster
Effect on human health Dr. Gerhard Scheuch GSBio-Inhalation GmbH Gemünden
Aerosol transport Prof. Dr. Hans-Joachim Schmid  Paderborn University
Air quality impact Dr. Sabine Wurzler  State Agency for Nature, Environment and Consumer Protection (LANUV) Essen
Recording of the event

Picture © Oliver F. Bischof

Marcel Philipp, the Mayor of the City of Aachen, opened the panel discussion with a special welcome. He did so in German language before the panel speakers switched to English. In the course of the evening, various aspects of aerosols in the context of Covid-19 were discussed in detail. Specific attention was paid to key points such as the transport and dispersion of aerosol droplets, the efficiency of different filtering face pieces and community masks, the role of indoor spaces, and implications of stay-at-home orders on ambient air quality. The panel also emphasized that the aerosol research community has much experience with aerosols and can therefore make an important contribution to understanding and dealing with this pandemic, jointly with medical doctors, epidemiologists and policy makers.

The event was open to the public but due to the regulations of the local Corona Protection Ordinance, only 40 guests joined the panel and the technicians on-site that evening. In addition, the discussion was streamed live on the internet for an international audience. Social distancing in the 45 meters long and 18.5 meters wide Coronation Hall with a very high ceiling was observed and all chairs were spaced well over 6 feet apart. The panelists could not speak with their masks on as unfortunately the acoustics of this ancient hall was very poor with so few people present.

In addition, Dominik Groth from TSI carried out CO2 measurements with a Q-Trak 7575 in the Coronation Hall from start to finish. In a room that is well-ventilated with outside air, virus containing droplets and particles are diluted. Therefore CO2 can serve as a proxy to determine when indoor air gets stale and a room needs ventilation. He first measured the ambient air outside Aachen Town Hall, which delivered the lowest value of the measurement series with 391 ppm of CO2. Once inside he observed an average value of 515 ppm CO2 before the start of the event and then kept moving around inside. At the end of the panel discussion, the CO2 concentration was still between 540 and max. 574 ppm, so the Coronation Hall only saw a moderate increase in CO2 during the event.

Picture © Oliver F. Bischof

Picture © Oliver F. Bischof


The organizers would like to thank all panel speakers, the city of Aachen for use of the Coronation Hall, the Conference Office of the RWTH International Academy for the organization onsite, Bergrath & Siebert GbR for the livestream and recording, and TSI GmbH for the CO2 measurements.