However, overall there is a lack of substantial evidence to support claims that facemasks protect either patient or surgeon from infectious contamination. More rigorous contemporary research is needed to make a definitive comment on the effectiveness of surgical facemasks.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4480558/#:~:text=The%20facemask%20has%20been%20used,contamination%20and%20surgical%20site%20infection.