On 5 May 2020, NATS, ACDA, Chorus America, and Barbershop Harmony Society co-sponsored a webinar on the scientific issues around singing during the pandemic that included specialists in aerosol science, laryngology, and other fields. This webinar sent shockwaves through the vocal arts communities, but also included critical information that we all need to know to assess how to move forward. You can watch the webinar here.
From CCDA (April 2021):third report of the International Coalition of Performing Arts Aerosol Study, the transmission of aerosols during indoor music-making can be significantly reduced through the adoption of specific mitigation strategies. These include specified face and wind instrument masks, along with 6 feet physical distance, ventilation recommendations, HVAC specifications, and other precautionary steps (such as washing of hands, using sanitizers). Read the report HERE.
Here is a summary of the issues involved with singing during the pandemic:
COVID-19 primarily spreads person-to-person via respiratory droplets that one emits when sneezing or coughing. These droplets are large enough (about 50 microns) that they can be seen. We also emit very small aerosol particles (as small as one micron) when breathing, speaking, or singing.
Aerosol particles may be more infectious than larger droplets, and they can remain in the air for long durations, whereas larger droplets tend to drop to the ground quickly due to their weight. Aerosol particles reach deeper into the lungs than larger droplets.
Singing produces six times the rate of small airborne droplets as speaking does.
When one exhales, mucosal fluid forms a film deep in the contracting lungs. When one inhales and the lung walls expand, the film bursts, creating aerosol particles that are then released into the environment. The rate at which one inhales or exhales affects the number of particles emitted. Deep, slow breathing followed by a fast exhale produces the fewest particles. The greatest particle release results from quick inhalation (causing a more violent film burst) followed by slow and prolonged exhalation. The latter describes the breath mechanism used in singing.
A similar film-burst effect happens in the larynx as the vocal cords expand and contract. The vocal folds vibrate more during singing than during speaking.
Volume also effects concentration, as louder vocal sound production results in larger concentration of droplets and/or aerosol particles. Thus, well-supported and produced singing can spread COVID-19 significantly more effectively than quiet singing or speaking or whispering.
Some people are “super-emitters,” spreading an order of magnitude more of these fine aerosol particles for an as yet unknown physiological reason. Singing in person is dangerous both for the reasons stated above and because we do not know who the super-emitters among us are. Some suggest that singing is essentially a "super-emitting" activity.