Physical force and velocity of expulsion from the respiratory tract determine not only the number of droplets that are produced, but also their size, although other factors play a role. This experiment demonstrated that with coughing more than half of the droplets that are produced are less than 10 micrometers in diameter. Over 80 per cent are less than 100 micrometers in diameter, thus may evaporate to droplet nuclei and may remain airborne.
