No air motion could be measured in 2 m distance in front of woodwinds which was the largest reach of aerosol clouds observed 17, 18. The plume generated by playing the clarinet has been found to be highly directional, to have high velocity, and to disperse quickly 21.

The local air concentration of aerosol has been found to decay to background level on a sub-meter length scale which indicates efficient aerosol dilution in the ambient air 19. The flow structures in the vicinity of woodwind players have been investigated to characterize the shape, extensions and particle size composition of the primary exhalation cloud 17– 20. Previous studies of aerosol emission during woodwind playing gained important insight on the structure and extension of the nearfield cloud and helped to specify distancing rules for avoidance of short-range exposure. Susceptible persons in the room are subject to what we call long-range exposure to infection risk 1, 5. When infectious, they produce a base level of infection risk which increases over time and does not depend on a susceptible person’s position in the room 1, 5. In absence of technical measures, such as capture-type ventilation hoods, aerosols will accumulate in the room air at largely homogeneous concentrations. While larger droplets (diameters > 50 µm) soon deposit due to gravitational settling or shrink to floatable aerosol particles 14, fine aerosol particles (with equilibrium diameters ≤ 5 µm) stay airborne and spread evenly in the surrounding air 15, 16. Susceptible persons in this region are subject to what we call short-range exposure to infection risk. Within this nearfield of a spreader disease transmission occurs in a discontinuous manner difficult to predict 13 and dependent on both distance and contact time. The primary aerosol cloud in the immediate vicinity of the player may carry pathogens in amounts sufficient to provoke quick infection of a susceptible person nearby. Woodwind instrument playing by an infectious person imposes disease transmission risk on other persons in the same room at two different scales of distance: Short-range and long-range. Infection risk calculations involve the aerosol emission rate as primary model parameter. Protective measures against aerosol transmission need to focus on ventilation and airing. Social distancing and face masks other than FFP2 protect susceptible persons from droplet transmission, but not from airborne transmission of SARS-CoV-2. Protection from aerosol inhalation requires wearing FFP2 masks which is not feasible for the player of a wind instrument. Orchestras, ensembles, conservatories, and music schools have a demand for reliable data on aerosol emission from wind instrument playing 12. Since increasingly infectious virus variants have developed during the pandemic, this question remains relevant for the music scene. Since even silent breathing generates aerosols 11 it is necessary to examine to which extent wind instrument playing possibly increases particle emission over normal breathing, without vocalization. Singing indoors has early been found hazardous 5– 7 and a correlation between voice activity level and aerosol emission rate is widely accepted 8– 10. Resulting attack rates depend on a plethora of factors, the most significant of which are the aerosol emission rate of the primary case and the dilution factor 5. Virus-laden aerosols exhaled by infectious persons are a potential source of secondary SARS-CoV-2 infections 1– 4. The pandemic of COVID-19 has forced many countries to shut down major parts of their public life, including the music business.

Particle playground emit over distance