Overview of Respiratory Aerosol Emission Measurements from the University of Bristol AERATOR and PERFORM projects

Justice Archer, F.K.A. Gregson, Allen E. Haddrell, Joshua Harrison, Lauren McCarthy, Henry Symons, Jianghan Tian, Christopher Orton, Natalie Watson, Brian Saccente-Kennedy, Ben Moseley, Ruth Epstein, James Calder, Pallav Shah, Declan Costello, Bryan R. Bzdek, JONATHAN P. REID, University of Bristol

     Abstract Number: 24
     Working Group: Aerosol Science of Infectious Diseases: Lessons and Open Questions on Models, Transmission and Mitigation

Abstract
Aerosol particles are exhaled during respiratory activities such as breathing while at rest or during exercise, speaking and singing and have the potential to transmit pathogens if emitted from an infected individual. Particle diameters can span more than 5 orders of magnitude and are exceedingly low in concentration when compared to particulate matter concentrations in room air, necessitating measurements in an ultraclean space where participants breathe in clean air. The coronavirus disease (COVID-19) pandemic has reinforced the need to understand respiratory aerosol particle and droplet emission rates.

The University of Bristol Aerosol Research Centre has led and participated in two significant measurement campaigns working with clinicians, and collecting data on respiratory aerosol from almost 300 participants. Now the outcomes of these projects are complete, we will provide an overview of the findings of the studies PERFORM (The Investigation of Particulate Respiratory Matter to Inform Guidance for the Safe Distancing of Performers in a COVID-19 Pandemic) and AERATOR (The AERosolisation And Transmission Of SARS-CoV-2 in Healthcare Settings).

In particular, we will summarise absolute number and mass exhalation rates from combined measurements of minute ventilation using cardiopulmonary exercise testing and exhaled particle concentrations. We will examine the correlation of particle mass emission rate with the flux of exhaled CO2, and summarise studies of droplet size distributions up to and above 100 micrometres diameter. The reduction in aerosol by surgical masks will be reported across a range of speech and language therapy tasks. We will also compare data from healthy adults and children with data from those with pre-existing lung conditions. The outcomes from our measurements with wind instrumentalists will also be summarised, comparing cohorts of trumpet, clarinet and flute players.