Jim Lee and Surya Venkatesh Dhulipala and Naomi Zimmerman and Mitch Weimer and Martin Wright and Steven N. Rogak
arXiv preprint arXiv:2105.12731
Publication year: 2021

Abstract: Airborne particles cause indoor transmission of COVID-19. Here, aerosol dispersion and removal in an unoccupied 4-bed hospital room was characterized using a novel aerosol tracer experiment. NaCl particle concentrations were measured around the room following a tracer aerosol release for 27 configurations of air purifiers and curtains. Tests without portable air purifiers produced an air exchange rate of 3.8-7.4. The transportation time between the start of aerosol injection and detection at other sensors was 1.3 – 3.6 minutes indicating that even smaller droplets would be well-dispersed in the room before being removed by the ventilation system or settling. Short curtains surrounding the beds had little effect on aerosol distribution while long curtains helped in increasing both the Air Changes per Hour (ACH) and transportation time. The best configuration was 4 purifiers (effective ACH: 11.6) in the corners of the room (with curtains) and exhausting towards the ceiling. Conversely, using two purifiers located between beds, with the exhaust directed to the center of the room produced a high level of mixing and could spread large droplets through the room.