Here's Arthur Firstenberg's enlightening compilation of the many studies showing, surprisingly, that masks DON'T prevent wound contamination during surgery.

(I included this in "Masking Ourselves to Death.")

https://www.facebook.com/revenuecameras/posts/arthur-firstenberg-on-facial-masksas-a-person-who-went-to-medical-school-i-was-s/2762572097350153/