A century after their introduction, are surgical masks necessary?
N L
NL
Belkin
D002986:Clinical Trials as Topic / Q000266:history; D049673:History, 20th Century; D008397:Masks / Q000266:history / Q000592:standards / Q000639:trends; D013530:Surgical Wound Infection / Q000266:history / Q000517:prevention & control*