SARS-CoV-2 and its ever-emerging variants, are spread from host-to-host
via expelled respiratory aerosols and saliva droplets. Knowing the
number of virions which are exhaled by a person requires precise
measurements of the size, count, velocity and trajectory of the
virus-laden particles that are ejected directly from the mouth. These
measurements are achieved in 3D, at 15000 images/second, and are applied
when speaking, yelling, and coughing. In this study 33 events have been
analysed by post-processing ~500000 images. Using these
data, the flow rate of SARS-CoV-2 virions have been evaluated. At high
concentrations, 10^7 virions/mL, it is found that 136 to 231 virions
are ejected during a single cough, where the virion flow rate peak is
capable of reaching 32 virions within a millisecond. This peak can reach
tens of virions/ms when yelling, but reduced to only a few virions/ms
when speaking. At medium concentrations, ~10^5
virions/mL, those results are hundreds of times lower. The total number
of virions that are ejected when yelling at 110db, instead of speaking
at 85db, increases by two to three fold. From the measured data analysed
in this article, the flow rate of other diseases such as influenza,
tuberculosis or measles, can also be estimated. As these data are openly
accessible, they can be used by modellers for the simulation of saliva
droplet transport and evaporation, allowing to further advance our
understanding of airborne pathogen transmission.