1/ Social distance, ballistic droplets, and aerosols: THE KEY ERROR

a) Chapin in 1910 figured out and insisted on the fact that close proximity led to increased transmission of respiratory diseases.

That empirical observation is correct, and social distance does reduce trans.

2/ (b) The key error (by Chapin) is the attribution (by Chapin of WHY distance works) to the ballistic droplets that fall to the ground & the dismissal of aerosols as causing this (even though they are so obviously more concentrated right in front of the person, like smoke)

3/ Over the years (a) has been seen to work well, including for COVID-19.

And epidemiologists & ID doctors see that, and resist any notion that (b) is wrong, because for them (a) and (b) are one and the same thing

4/ Once we separate (a) and (b), we can keep (a: distance works to reduce trans.), and correctly realize that it works **because of aerosols.** And discard (b), realizing droplets only in cough/sn

And then the measures to control aerosols in shared room air are totally natural

5/ Chapin's book. Read at least the end of the chapter on airborne transmission, it is illuminating and it is the reason why we are in this predicament.

https://archive.org/details/sourcesmodesofin00ch

6/ Article on this history with @linseymarr @EThomasEwing Katie Randall, and Lydia Bourouiba coming soon to a preprint server. https://twitter.com/linseymarr/status/1278036517890347008