While trying to rescue Pavel Chekov from 20th century medicine, James T. Kirk, Gillian Taylor, and Doctor Leonard McCoy wore surgical masks to blend in with the other staff members. (Star Trek IV: The Voyage Home) In 2368, Berlinghoff Rasmussen mentioned that he and a colleague had visited a 22nd century ship. Beverly Crusher replied that he likely saw surgical masks and surgical gloves. (TNG: "A Matter of Time" )