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COVID-19 NFHS Study Update

As of today (April 19th, 2021), we have some important updates on the current state of the COVID-19 pandemic and congregational singing. Many of you will be aware that a large number of public education organizations have been sponsoring a scientific study out of the University of Colorado Boulder and the University of Maryland. That study has just released another update on their findings and updated their recommendations. Below is a link to the full paper, important excerpts that pertain to congregational singing, and my personal summary of the new information.


Full Paper Link

NFHS Scientific Study Prepress Paper (40+ Pages) (April 15th)

Important Excerpts

  • Using masks greatly reduced the aerosol concentration measured in front of the source. Plumes from talking, singing, and performing musical instruments were highly three dimensional and vary considerably in time and space. The plumes decayed rapidly and are highly unsteady, which lead to large variations in our plume-level measurements. In addition, our flow characterization data show that when masks were used, plumes were shorter and plume velocities decreased, which decreased the trajectory of highly concentrated jets of aerosol.
  • CFD modeling showed differences between outdoor and indoor environments of singing and playing the clarinet without masks. In an outdoor environment, ambient wind breaks the musician’s thermal plume and expelled airflow and accelerates the dilution of aerosol. In an indoor environment, the musician’s thermal plume and expelled airflow contribute to the spread of aerosol due to space confinement. In addition, the indoor walls force the formation of smaller eddies, and the consequent distribution of the particles. To minimize infection risk to musicians and audiences via aerosol, this study showed lowest risk with an exposure duration less than 30 minutes for indoor singing and clarinet playing, and an exposure duration less than 60 minutes for outdoor performance.
  • Face shields are only effective at close range to stop large droplets (such as the visible droplets from a cough or sneeze) and do not prevent aerosol from being emitted or inhaled. Much of the respiratory particles emitted are small in diameter and follow streamlines around face shields.
  • 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.
  • If indoor spaces are used, we 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. For a room that has three air changes per hour, one air change is 20 minutes.


My Recommendations/Summary

  • This new information reinforces the importance of proper mask-wearing.
  • In general, outdoor events are significantly safer than indoor events.
  • This new information reinforces the difference been shields and masks. Shields do not protect the wearer or other from aerosol transmission.
  • Air circulation, distribution, and “air changes” are key components to virus spread through aerosols. However, air circulation and distribution are unique to each building and room and highly effects how much and where aerosols may spread. Unless you have an airflow expert analyze your rooms, this is a big variable that makes comparing situations between churches nearly impossible.
  • The authors of this study are not recommending any distancing beyond what the CDC recommends. The current CDC recommendations for communities of faith (found here) are the same as their general social distancing recommendations: 6 feet.
  • These recommendations remain true for fully vaccinated individuals as per the CDC guidelines for fully vaccinated people here.


For more updates and resources on COVID-19 and congregational singing, please go to:

This update is written by Center Director Brian Hehn and should be used only as general advice in consultation with other trusted sources. This is his personal summary of the data presented and should not be considered scientific fact nor medical advice.

18 thoughts on “COVID-19 NFHS Study Update”

  1. Jim and Susie S Miller says:

    Simply stated, although this article contains a lot of information, we need not change much from what we have been doing. So we will still follow the recommendations of CDC.

  2. Carol Longsworth says:

    THis study does not indicate the space limit the aerosols
    travel. 4 feet? six feet? It seems that solo singing or a spread-out trio or quartet in a large auditorium could still be safe. (?)

    1. admtcfcs says:

      I believe that those distances were covered in earlier parts of the study. You’ll need to go back to earlier releases for that data.

  3. Judy Humphrey-Fox says:

    This doesn’t say why we still need to be this cautious when we are vaccinated. The government said, “Get vaccinated so life can get back to normal.” But even though so many of us are vaccinated, very little has changed.

    1. admtcfcs says:

      We are just now (as of today) at around 1/3 of our country’s population being fully vaccinated. That is good, but it is not enough to prevent community spread of the virus. It takes a large percentage (between 70 to 85%) to reach what is reffered to as “herd immunity” which prevents community spread of a virus. So we’re on our way, but we’re not there yet.

  4. Noel Werner says:

    This study derives the 30-min and 60-min limits from the assumption that there is continuous singing and playing in a rehearsal. Are the time limits different for masked/distanced congregational singing of two or three 3-min hymns in the course of a single service?

    1. admtcfcs says:

      We have not seen a study that deals with that specific situation.

  5. Shirley Durr says:

    Yes. Vaccinations do not cure diseases. They control it but only if enough people are vaccination. Think of polio, mumps, measles, etc. Those diseases still exist where people are not vaccinated and there was an increase in measles outbreaks in the U.S. when anti-vaxxers encouraged people to not vaccinate.

    Also think of the flu. I used to get the serious flu several times a year and it would last for a week or more. Once I was even hospitalized for it. Then I started getting a flu shot every year; I still get the flu. But now it lasts about 3 days and is never a serious case.

    Vaccinations are not cures but they do control diseases.

  6. Susan Gillespie says:

    2 things about the vaccine: 1) no vaccine is 100% effective; 2) how effective it is in any individual is unknown (for example, some medications make it less effective). Which means each of us has more freedom than we would otherwise, but as those who organize group activities we must be responsible to make things as safe as possible.

  7. PastorS says:

    Judy, why not, when we can potentially preserve the health of others? I don’t see wearing a mask as deviating far from “normal.,” especially compared to isolation.

  8. Rebecca Patterson says:

    Does it matter what percentage of the congregation is fully vaccinated? Can’t a congregation that is 90% fully vaccinated sing safely, no matter what the vaccination rate in the community or the nation?

    1. admtcfcs says:

      Yes, individual congregations and communities need to make their own decisions based on their local metrics and local/state guidelines. We cannot make individual recommendations for local congregations or regional bodies.

  9. Joy Ackerman says:

    Question for admtcfcs: What is the risk level of congregations humming along (masked) when hymns are played? (Services are in-person at 1/4 capacity, masks required, household groups 6′ apart, UV light system in HVAC, and air in constant circulation.)

    1. admtcfcs says:

      We have only seen one study to include humming. That study seems to indicate that humming creates more aerosols than normal breathing, but less aerosols than speaking, shouting, or singing. So on the scale of risk-factors, humming is lower risk than singing.

  10. Monica Rossman says:

    Any comments on the latest CDC guidelines (as of May 13, 2021) that masks are no longer required indoors for fully vaccinated people? Specifically, what are your thoughts on how (if at all) group singing indoors should be affected by these new guidelines? I believe indoor group singing remains risky, given current US vaccination rates, & I remain skeptical that anything about indoor group singing should change at this point..

  11. Gregory Kruse says:

    If the study doesn’t pertain to singing hymns and reciting psalms in church, what good is it? Furthermore, parishioners of the Presbyterian Church are not the general public. In my opinion, those who feel a need to worship with other Christians are being deprived for no good reason.

  12. Bill says:

    Latest CDC guidelines show singing in the “green” for vaccinated folks. Why is this still indicating otherwise???

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