Over the past few years, musicians and scientists have become aware of the risk of spreading Covid-19 during orchestra practices. Even the Vienna Philharmonic conducted a study to investigate the risk their instruments posed to people sitting nearby. Now, a recently published study by researchers from Colorado State University further confirms that wind instruments, in particular those of the brass family, are most likely to spread respiratory particles.
Brass instruments such as trombones are the biggest spreaders of aerosols, according to a new study.
Aerosol expert and professor of mechanical engineering John Volckens and his colleagues at CSU worked with 81 volunteer musicians to measure how different wind instruments spread respiratory particles and what measures could be used to reduce the risk. Using an aerosol measurement chamber, they detected aerosols of different sizes and looked at how many each instrument produced. Notably, some instruments were bigger spreaders than others. On average, brass instruments like tuba, trumpet and trombone spread almost three times as many aerosols as woodwinds such as oboes, clarinets or bassoons.
To put this into a bit of context, singing was in the same ballpark as the brass instruments and there have been known reported outbreaks of Covid-19 spread through choir rehearsals.
One way to reduce the risk from trumpets, tubas and trombones is by using bell covers, which capture particles coming from the end of the instruments. However, in a statement to CSU, Volckens cautions that this is likely not enough. “The data suggest that masks and bell covers cut down half to 75% of particles coming out of the mouth or instrument. And the reason blue surgical masks or bell covers don’t work better is that they’re just not a tight fit. These devices don’t achieve an N95 level of protection.” In addition, bell covers didn’t seem to have much of an effect for oboes and clarinets, and there wasn’t enough data to determine whether they worked for several other instruments.
Knowing what we know now about the way Covid-19 is spread by air and how much brass and woodwind instruments can contribute to this, Volckens also emphasized that shutting down music venues and rehearsal spaces early in the pandemic has likely saved lives. “I really want to honor them by acknowledging that decision and the economic and mental hardships that followed,” Volckens said. “Thank you for making a really hard sacrifice on our behalf.”
At the moment, many orchestras and bands are back to regular rehearsals, with varying levels of safety precautions. But understanding exactly which instruments are the biggest spreaders of aerosols will be useful for any future outbreaks of respiratory infectious diseases (or the next big wave of Covid-19, because that hasn’t gone away yet!)
