  Activities such as singing or playing a wind instrument release respiratory
particles into the air that may contain pathogens and thus pose a risk for
infection transmission. Here we report measurements of the size distribution,
number, and volume concentration of exhaled particles from 31 healthy musicians
playing 20 types of wind instruments using aerosol spectrometry and in-line
holography in a strictly controlled cleanroom environment. We find that playing
wind instruments carries a lower risk of airborne disease transmission than
speaking or singing. We attribute this to the fact that the resonators of wind
instruments act as filters for particles >10 $\mu$m in diameter. We have also
measured the size-dependent filtering properties of different types of filters
that can be used as instrument masks. Based on these measurements, we
calculated the risk of airborne transmission of SARS-CoV-2 in different near-
and far-field scenarios with and without masking and/or distancing. We conclude
that in all cases where there is a possibility that the musician is infectious,
the only safe measure to prevent airborne transmission of the disease is the
use of well-fitting and well-filtering masks for the instrument and the
susceptible person.
