Consolidated COVID-19 Conclusions/Mitigation Guidelines
Summarized from 2 Studies on Aerosols Cited Below

As of April 28, 2021 summary of guidance from the studies presented below.
For more detailed and up to date information refer back to the original studies (NFHSA/UC Boulder/UMD and CSU).
CSU provided updated study results on May 21, 2021 - and are noted below, summary of guidance does not change.

CBDNA/NFHS COVID-19 Video, 20 April 21: "COVID-19 Mitigation Strategies for Music"

Found at:


From scientific preprint of the research paper: "Measurements and Simulations of Aerosol Released while Singing and Playing Wind Instruments" -  April 13, 2021 


  • Masks and Bell Covers- Well fitting masks for singers and musical instruments - were found to be effective at “decreasing aerosol and larger droplet emissions” from musical performance. 
    • A note on bell covers for woodwind instruments They found that air and particles do escape from keyholes but found the number of “particles was minimal” and that using a “bell cover eliminated a majority of the aerosol coming from the instrument.”  Due to the difficulty in playing a woodwind instrument in a bag, they “recommend bell covers as the main control measure for woodwind instruments.”
    • A note on material for bell covers- “Standard 3-layer surgical masks were used for small instruments, such as woodwinds. Large instruments were tested with Merv-13 material inside of a nylon spandex material.”  They do not recommend bell covers made from  a “stretchy material such as spandex” as it is easy for aerosol to pass through.
  • Face Shields-  are “only effective at close range to stop large droplets”  and “do not prevent aerosol from being emitted or inhaled.”  
  • Plexiglass/Plastic/Glass Barriers are Not Recommended- read the report for explanation of why these measures were found not to be effective.
  • Social Distancing Recommended - “Performers should follow social distancing protocols as recommended by the CDC for music activities. Aerosol concentrations are highest closest to the source, both inside and outside, and decrease with distance.”
  • Rehearsal Space Preference Order- they recommend that performances/rehearsals happen outdoors, if not possible then they have provided recommendations for indoor venues.
      1. Outdoors

      2. Indoors with elevated outdoor air exchange rate from HVAC
      3. Indoors with typical outdoor air exchange rate from HVAC plus recirculation air through MERV 13 filters or addition of appropriately sized HEPA air cleaners
      4. Indoors with outdoor air exchange rate from open windows supplemented with appropriately sized HEPA air cleaners when airflow is reduced under certain outdoor wind conditions.
  • Limiting Rehearsal Time- for indoor rehearsals  they recommend “having at least three air changes per hour in the rehearsal room and limiting rehearsal time to 30 minutes at a time before leaving the room for at least one air change.”
  • HEPA Air Cleaners to Supplement Ventilation- For indoor spaces, they recommend  HEPA air cleaners.  

From Colorado State University Study  “Reducing Bioaerosol Emissions and Exposures in the Performing Arts: A Scientific Roadmap for a Safe Return from COVID19”  December 2, 2020 update and May 21, 2021 update

 Recommendations/Findings from Round 2

  • Some instruments produce more aerosols than others
  • “Bioaerosol emissions can vary massively from one person to the next.”
  • “Masks and bell covers appear to be effective.”

 Recommendations/Findings from Round 3

slide 36:

  • "Results suggest that brass instruments tend to have higher particle emissions than woodwinds…BUT the “player effect” is likely larger than the ”instrument effect"... Meaning that almost ALL instruments have the potential for high emissions."
  • "Bell covers on brass instruments (single air exit) make sense."
  • "Bell covers on woodwinds (multiple exit paths for air besides the bell) show mixed results."

slide 48:

  • We still do not know (as a scientific community) how many COVID19 virions it takes to produce an infection in humans.
  • Although we cannot define absolute risk, we can define relative risk. Look for continued guidance from our group and others in the coming months.
  • Get vaccinated!

Video of NASM Webinar presented by Dr. Volckens which took place on May 20, 2021:


From the  CBDNA/NFHS 3rd Release of Preliminary Results November 13th

5 take aways



 also published separately at:


Website Citations:

Spede, Mark, et al. “Unprecedented International Coalition Led by Performing Arts Organizations to Commission COVID-19 Study.” NFHS, National Federation of High School State Associations, 28 Apr. 2021, 11:00 am, 

Spede, Mark, and James Weaver. “COVID-19 Mitigation Strategies for Music.” YouTube, NFHS, National Federation of High School State Associations, 20 Apr. 2021, 

Volckens, John, et al. “Reducing Bioaerosol Emissions and Exposures in the Performing Arts - School of Music, Theatre and Dance.” School of Music Theatre and Dance, Colorado State University, 28 Apr. 2021, 12pm, 

Volckens, John, et al. “Reducing Bioaerosol Emissions and Exposures in the Performing Arts - School of Music, Theatre and Dance.” School of Music Theatre and Dance, Colorado State University, 2 June. 2021, 3pm, 


 June 3, 2021