Do surgical masks generally reduce microbe colonies in operating rooms?
A study published by the journal Clinical Orthopaedics and Related Research in 1975 found that the number of microbe colonies "jumped dramatically" (by 34 times) when people wearing surgical masks entered empty operating rooms, and the count of microbes "was no different than" when no one in the room wore masks. A similar study published by the same journal in 1999 found that regardless of whether everyone or no one wore surgical masks in an operating room and in the hallway outside of it, there was "no effect on the bacterial counts in either the hallway or the operating room." Such results, along with at least 18 other studies in science journals, show that contagious respiratory diseases are mainly spread by microscopic aerosols that easily penetrate surgical and cloth masks. Ultraviolet disinfection systems are highly effective at killing the microbes in such aerosols, and they have been successfully used to control the spread of contagious diseases in hospitals and schools.