Say It Don't Spray It! Large Droplet Emissions from Speaking, Singing, and Playing Wind Instruments

KY TANNER, Kristen Good, Dan Goble, Nicholas Good, Amy Keisling, Christian L'Orange, Emily Morton, Rebecca Phillips, John Volckens, Colorado State University

     Abstract Number: 182
     Working Group: Aerosol Science of Infectious Diseases: What We Have Learned and Still Need to Know about Transmission, Prevention, and the One Health Concept

Abstract
At the onset of the COVID-19 pandemic, the leading mitigation strategy endorsed by public health experts was 6’ physical distancing coupled with regular hand hygiene. Since then, we have learned that the primary transmission mode for the virus is through the airborne transmission of aerosols (dp < 100 μm) and/or “ballistic” droplets (dp > 100 μm) that emanate from the human respiratory tract. This work sought to characterize the emission rate and size distributions of large droplets (dp > 20 μm in aerodynamic diameter) produced by a panel of 53 volunteers while talking, singing, and playing wind instruments, with and without face masks (while singing) and bell covers (while playing wind instruments). Participants performed these activities inside a cleanroom, with droplet emissions sampled via water-sensitive-paper cards in the immediate vicinity of their mouth (or instrument bell). Cards were analyzed using a microscope and image processing software (ImageJ) to determine number and size distributions. We modeled droplet size and concentration at the point of release, accounting for travel distance, dispersion, settling, and evaporation. Average particle emission rates varied from 5.3/min (SD = 3.3/min) for singing with a mask to 178/min (SD = 181/min) for talking without a mask. On average, talking produced the most droplets followed by singing without a mask and then instrument playing (negligible difference between with and without bell covers). However, we found large variations in emissions between individual participants for every performance category. Age and sex were not significant predictors of emissions, contrary to previous findings for smaller particle sizes. Size distributions were similar across performance categories (CMD = 55.5 μm, GSD =2.09). Bell covers did little to mitigate large droplet emissions from most wind instruments, but face masks greatly diminished large droplet emissions associated with singing.