1). you can’t use your hand or sleeve to cover your cough or sneeze when scrubbed in a case. 2) see number one - it keeps snot/ gum/ gross contamination out of the surgical field.
Thank you.
Surgical masks are for large particle sizes, but not to stop 0.125 micron particles such as Covid.
N95 masks filter 95% of particles larger than 3 microns per standards.
Stopping Covid particles requires SCBA or other supplied air systems.