Department of Physics Colloquium

General Physics Colloquium, Prof. Eberhard Bodenschatz, Cornell University

Title:  Human Aerosols and Drops

Host:  Chris Myers

Abstract:  COVID-19 and other airborne diseases are transmitted to healthy individuals through the inhalation of pathogen-containing particles exhaled by infectious individuals. I will provide an overview of the physics involved in the formation of these particles and the effects of social distancing and masking on transmission risk. I will present the results of our experimental study to characterize the size distribution of exhaled particles using aerosol size spectrometers and inline holography across the particle spectrum of human droplets and aerosols from nanometers to millimeters.  Breathing maneuvers studied in more than 200 volunteers aged 5 to 80 years included mouth/nose breathing, loud/normal speech, lay person and professional singing, humming, shouting, coughing, and playing wind instruments. Based on these results, the physical basis of exhalation flow, the leakage from face masks of various types and fits measured in human subjects, the consideration of particle shrinkage in the environment due to evaporation, and the rehydration, the inhalation ability, and the deposition in the sensitive airways, I will establish the upper bound of transmission risk for SARS-CoV-2 for one-to-one exposure. I will demonstrate that wearing appropriate masks in the community provides excellent protection for others and oneself and eliminates the need for social distancing.