If you haven't seen it already, there is some preliminary data from a study of aerosol production for vocalists and brass and woodwind instruments out of the Colorado. The URL is https://www.nfhs.org/media/4029952/preliminary-testing-report-7-13-20.pdf?fbclid=IwAR1QMaQpjx04RQxeExcHekDjDiP82iE4xtDXDk2xN5RDBqAA-iHuaGtNDQA. There are some reasonable recommendations at the end. Two takeaways that I had (I am a musician and a chemist) were that if there were going to be rehearsals with more than one player, they should be 6" apart (9" for trombones) and the horns all need to be masked. Safest would be 36 square feet per person. So for a 100 piece orchestra, 4,000 square feet would be ideal. Could probably get away with less on the sides. Puppy pads are necessary for brass, but then the people picking them up should wear gloves, treat it as biohazardous materials (special bagging) and then wash up after. Another issue is the air exchange rate. Given the example in the slides, I have a chart from which we can extrapolate that it will take about 150 minutes for the air to totally exchange (unless if there are HEPA filters installed) in a large rehearsal hall, so rehearsals with a 10 minute break between rehearsals will not allow for effective clearing of virus that might be aerosolized in a large room. It looks like in the example they worked with 3ACH. With 4 ACH it takes about 117 minutes to refresh the air in a medium-sized clinic, according to my wife, who works in one. Interpolating with a 3ACH rate, it would require over 150 minutes to do the same, assuming a linear relationship (which very well may not be true; others in this list serve will know better than I). The horn mask data looked pretty good, but I'm concerned about aerosolization (which wouldn't necessarily show up in the Schlieren optics). The trombonist's arm movement, for example, will spread the aerosol. I'm also concerned about the cleaning of the nylon, which should be done every day.
We are still working out what we are going to do at Texas Tech for anything that is indoors. Maybe chamber ensembles for the fall? Band, orchestras, and choirs? We are looking at large rooms, short rehearsals, no audiences, and masks.
I don't know if this helps, other than to say that we are all struggling trying to sort out how to make music and do rehearsals in the time of CoronaÉ
Dominick J. Casadonte, Jr.
Minnie Stevens Piper Professor
Fellow, American Chemical Society
TTU President's Excellence in Teaching Professor
President's Award for Excellence in Science, Mathematics, and Engineering Mentoring (PAESMEM) Awardee
Department of Chemistry and Biochemistry
Texas Tech University
Lubbock, TX 79409
I have a non-chemical safety question for you. This is a talkative bunch with many opinions on many subjects, so I figured it's okay to be off topic. I am particularly interested in your opinion if you are at an institution in MA. Is your institution permitting your music/theater folks to do indoor singing or playing of wind instruments for the Fall? Curious of your or your colleagues opinions on this. Mine is that this is currently not permitted under theatre and performance sector specific MA reopening guidelines (even though those technically apply to only performances and not classes). I think it's splitting hairs to say it's different if they are in front of an audience or not. What are your thoughts?
Kristi Ohr, Ph.D. (pronouns: she/her)
Chemical Safety Services Manager
Environmental Health and Safety
40 Campus Center Way
Amherst, MA 01003
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