Scientists from the University of Utah began their research in the summer of 2020. Then the musicians wanted to know how and when they would be able to perform music again with minimal risk of coronavirus infection. Before that, at music rehearsals, there have already been cases of mass infection: COVID-19-19, 53 of the 61 members of the Skagit Country Choir fell ill.
Scientists have created computer models of the concert hall, taking into account not only the floor plan, but also each air flow and the frequency of operation of air conditioners. On the diagram, they marked the most typical places occupied by various musicians. In the case of the Utah Orchestra, this was the standard arrangement – with strings in the front, then several rows of winds, the back row was occupied by the percussion section and trombones.
To model the spread of infection in a concert hall, the authors used data previously obtained by scientists from the University of Minnesota. They estimated what concentration of aerosol, which could potentially contain viruses, is created when playing different wind instruments. It turned out that the greatest risk in this context is presented by trombones and trumpets.
Using a computer simulation of fluid dynamics, scientists have learned how air and aerosols can circulate in a concert hall where the Utah Orchestra is playing. The air in the room was moved down from the feeders on the ceiling, and then returned to the intake pipes behind the stage. At this time, two large eddies of air were formed – in front of the stage and behind it. Scientists have compared them to a tornado. They helped to keep the aerosol in place.
It turned out that streams of aerosol from wind instruments, primarily pipes, pass through the breathing zone of percussionists. The scientists decided to transplant the musicians. They understood that this was not an easy task, because the location of the orchestra members was connected both with tradition and with acoustics. However, the musicians agreed to make any changes.
Scientists have proposed to transplant the trumpeters to the back row, in the immediate vicinity of the hood. Other “blowers” were moved from the center to the sides – closer to the stage doors and the hood. At the same time, the doors had to remain open. The musicians, whose playing is not associated with the formation of aerosols, were placed closer to the center in the middle.
These permutations, scientists hope, would allow the aerosol to leave the concert hall, bypassing the musicians’ breathing zones, and not get into the eddies of the air. According to a computer model, the amount of aerosol in the air after that should have been reduced by hundreds of times. Although the direction of the air flow may differ from concert to concert, the general ventilation principles should be the same.