Dr. Christof Asbach

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Dr. Christof Asbach studied electrical engineering at the University of Duisburg. In 2004, he received his PhD from the University of Duisburg-Essen for the development of a system to accurately measure fine dust particle concentrations in the atmosphere, taking into account the loss of semi-volatile particles. During a two-year post-doc at the University of Minnesota, he developed protection schemes to avoid particulate contamination in the microchip production using extreme ultraviolet lithography (EUVL). Dr. Asbach has (co-) authored over 150 publications including approximately 100 peer-reviewed papers. Since 2020, he is president of the aerosol research society for the German-speaking countries (Gesellschaft für Aerosolforschung, GAeF). In this position, he has coordinated the writing and publication of a well-received and cited GAeF-position paper on the role of aerosol particles in SARS-CoV-2 infection and has been frequently interviewed for various national and international TV- and radio stations on this topic.

Air Filtration Solutions to Minimize Infection Risks

Respiratory infections often occur through the inhalation of airborne pathogens like SARS-CoV-2. These viruses can become airborne with liquid aerosol particles exhaled during normal breathing, speaking, singing, coughing, or sneezing. Once airborne, these liquid particles undergo dynamic changes, i.e., they shrink due to evaporation of the liquid phase, while the residual particles are transported in the air due to e.g. inertia, sedimentation, advection and thermal buoyancy. Two different possible routes of infections need to be distinguished, direct and indirect infections. Whereas a direct infection means that the aerosol plume exhaled by an infectious person is directly inhaled by another person, indirect infections occur, when the exhaled viruses are not removed from the air space, therefore accumulate over time and an increasing virus concentration is inhaled by other persons in the same air space. Indirect infections are a substantial risk in closed indoor environments with no or poor air ventilation, whereas they are nearly impossible outdoors, where the exhaled breath is quickly dispersed and virus concentrations diluted due to ubiquitous natural air flows. Various air filtration solutions are readily available to minimize infection risks, of which face masks, air purifiers, and HVAC systems are the most prominent. Each of the solutions has their own advantages and disadvantages. The presentation will introduce the various filtration solutions and discuss their pros and cons. Experimental data on the efficacy of the different measures will be provided and conclusions drawn towards their effectiveness to lower infection risks.