At that time there were no universal standards, Ben. Some surgeons worked in gowns, caps and masks, while others wore only an apron to protect their clothing. Some used rubber gloves, others felt that they could work with more finesse if their hands were well scrubbed but uncovered.
Certainly the ancillary personnel present, like surgical nurses or an audience of students, generally were not masked. The modern ideal of aseptic surgery, in which surgical teams work in a completely germ-free environment in which even the incoming air is filtered, was beyond the technology available at that time. So they relied more on the use of chemical antiseptics which were hostile to microbes in the immediate area of the wound. This was generally effective, but could be damaging to the patient's own tissues.
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