Here is a paper you can peruse if you want to learn a little
more about airborne virus particles and how they are studied.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2546863/
Nothing there is news to me. I used to DESIGN instrumentation to make these kinds of measurements. The key fact is that the particles are NOT “viral”, they are liquid, and act exactly the same whether the infective agent is a virus, a bacterium, or a spore. Anybody who pontificates about the size if a virus particle when talking about airborne transmission or masks, they are just blowing smoke.