University of Colorado calibrate scholar Tehya Stockman places a homemade bell cover made from aesculapian mask material to test for the effectiveness of lowering aerosols. Glenn Asakawa/University of Colorado Boulder
To find answers, James Weaver, EdD, film director of performing arts and sports for the National Federation of State High School Associations, and Mark Spede, DMA, national president of the College Band Directors National Association, sought assistant from Shelly Miller, PhD, MS, a professor of mechanical engineering and staff in the environmental engineer program at the University of Colorado. Miller teamed up with Jelena Srebric, PhD, professor of mechanical technology at the University of Maryland, and Jean Hertzberg, PhD, associate professor of mechanical engineering at the University of Colorado, to measure the aerosols produced during musical performances, visualize their run around the room, and test ways to reduce the gamble of SARS-CoV-2 transmission.
To pay for the study, published in the american Chemical Society journal ACS Environmental Au, Weaver and Spede raised $ 330 000 over 22 days from 125 arts organizations around the worldly concern. “ [ The pandemic ] brought many divergent arts organizations together with a common goal, ” Spede said in an interview.
early on, the function of aerosols in spreading SARS-CoV-2 wasn ’ thymine clear. But outbreaks linked with indoor gatherings suggested that people could be infected entirely through aerosol exposure. A Washington State chorus practice that became a superspreader event in mid-march 2020 highlighted the gamble of aerosol transmittance linked with performances :
- sixty-one people, including 1 who had COVID-19 symptoms, attended the 2.5-hour rehearsal .
- At least 52 developed confirmed or suspected infections, 3 were hospitalized, and 2 died .
Miller and her colleagues analyzed the event and found the virus most likely spread via aerosols. Their data besides showed that :
- The infection rate could have been reduced from 85 % to less than 10 % if the rehearsal had lasted 30 minutes rather of 2.5 hours .
- multiple moderation strategies like wearing masks, limiting rehearsal time, using a portable air filter, and improving breathing in the rehearsal board could reduce the risks flush further .
“ We knew that sing was hazardous because there were confirmed outbreaks, but we knew nothing about melodious instruments, ” Tehya Stockman, the study ’ s lead writer and a alumnus scholar at the University of Colorado, said in an interview.
The investigators quickly launched the Performing Arts Aerosol Study to learn more about aerosol plumes released from instruments and during other types of performances. “ We were in truth trying to think about what moderation strategies would work for kindergarten through college students learning music, ” Stockman said. In the study, she and her colleagues :
- Used tune cleaners with high-efficiency particulate air out filters to lower ambient particles and reduce electric potential background aerosol levels .
- Invited 2 singers, 1 field performer, and 12 instrumentalists who played 5 unlike woodwind instruments and 4 boldness instruments to participate .
- Measured plumes of aerosols and carbon dioxide emitted during each performance .
The results showed that the instruments produced more aerosols than speak and about the same amount as scorch. “ We learned that the plumes are quite complex, ” Stockman said. “ They are very transient, and the aerosol concentration varies quite a piece from instrument to musical instrument. ”
future, they tested several extenuation strategies that included masking the instruments. One approach used a 3-layer surgical mask secured with a rubber band over the doorbell of small instruments. Another covered the bell of larger instruments with filtering material having a minimum efficiency reporting rate of 13 ( MERV 13 ), which is recommended for non–health caution facilities. These techniques were able to :
- Reduce aerosol concentrations to amounts comparable with setting levels .
- Decrease the distance that aerosols project beyond the bell, from 12 in to 3 in .
- Slow the accelerate of an initial aerosol feather, allowing ambient air out to dilute it before reaching performers .
“ A bell cover reduces the risk enough to a reach it a viable scheme for people to use, ” Stockman said. Mutes, which fit into an instrument ’ randomness bell to change its note, allowed aerosols to escape “ like a ovolo on a garden hose, ” Spede noted.
Using calculator model, Stockman and her colleagues besides found that performing outdoors and limiting a performance ’ south duration can protect musicians from aerosol accumulation. “ Aerosol can build up over time much more quickly in an indoor quad, ” she noted.
The team ’ second calculations showed that combining prevention strategies was the most effective approach, providing the succeed risk-reduction effects :
- Wearing masks and keeping performances to 30 minutes or less kept the hazard of infection below 10 % .
- Performing for more than 30 minutes, even with masks, led to infection risks greater than 10 % .
With help from Weaver and Spede, the researchers developed recommendations for multiple precautions that could be applied in music classrooms. “ [ Mitigation strategies ] had to be easy to use, easy to access, and relatively low-cost, ” Weaver said in an interview. They include :
- Having singers, theater performers, and musicians wear well-fitting surgical masks while singing or speaking .
- Using bell covers made of a 3-ply surgical mask for small instruments or a MERV 13 filter inside a Spandex cover for larger instruments .
- Maintaining US Centers for Disease Control and Prevention–recommended social outdistance between performers and audience members .
- Limiting performances to 30 minutes indoors and 1 hour outdoors. A recent update extended indoor operation fourth dimension to 50 minutes at venues with 3 air travel exchanges or more per hour .
- Performing outdoors when potential .
- Improving breathing indoors by opening windows, using high-efficiency particulate air cleaners, or increasing the breathing organization ’ s atmosphere change rate .
To assess the real-world consequence of implementing the recommendations, Spede and Weaver teamed up with Whitney Huang, PhD, an adjunct professor of mathematics and statistical sciences at Clemson University. Their view of 3000 schools with in-person music teaching end year showed that closely 2800 used some of the recommend precautions.
Based on SARS-CoV-2 transmission patterns in the schools, the trio concluded that the find of contracting COVID-19 during rehearsal with the recommend mitigations in space is about 1 in 2 million compared with about 1 in 270 000 without the precautions.
“ If we can get used to using these mitigations, we can continue operating at very broken risk, ” Spede said.
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Conflict of Interest Disclosures: none reported .