Virginia Postrel walks through the history of medical face masks:
19th century
Fashionable women wear lacy veils to protect against dust, particularly from the disruptions of Georges-Eugene Haussmann’s remaking of Paris. As germ theory spreads, the fashion takes on a medical aura when researchers using microscopes find bacteria on dust particles.
In an 1878 article printed in the Hospital Gazette and in Scientific American, A.J. Jessup, a Westtown, New York, physician, recommends cotton masks to limit contagion during epidemics:
Thus we see that as quarantine and disinfection will certainly spread of contagion from patient to patient, may we not confidently hope, by preventing the entrance of germs into the lungs and blood, by a properly constructed filtering mask to yet witness the spectacle of a population walking about the streets of a cholera infested city, without fear of its infection however deadly. As a properly made cotton filter worn over the mouth and nose must shut out all atmospheric gems of the ordinary putrefactive kind. We may confidently assured that those of disease will be equally excluded.
He cites his experiments with test tubes with and without cotton stoppers. His idea does not catch on.
Early 20th century
Although the first study advocating the use of masks during surgery is published in 1897, they are rare at the turn of the century.
In 1905, Chicago physician Alice Hamilton publishes an article in the Journal of the American Medical Association, reporting on experiments measuring the amount of streptococci bacteria expelled when scarlet fever patients cough or cry. She also measures the strep bacteria from healthy doctors and nurses when they talk or cough, leading her to recommend masks during surgery.
“I was told by a student in a large medical college in Chicago,” she writes, “that he had often noticed at the clinics of a certain surgeon that, when the light was from a certain direction, he could see, from his seat in the amphitheater, a continuous spray of saliva coming from the mouth of the surgeon while he discoursed to the class and conducted his operation. Obviously, protection of the mouth, of some sort as to catch and impression the droplets of sputum, should be a routine precaution for surgeons and for surgical nurses during operations.”
In 1910, an epidemic of pneumonic plague strikes Manchuria. Appointed by the Chinese court to head anti-plague efforts, the Penang-born, Cambridge-educated physician Wu Lien-Teh (Wu Liande) argues that the disease is transmitted through airborne contact. To prevent its spread, he develops masks to be worn by medical personnel and the general public.
During the 1918 global flu epidemic, medical personnel routinely adopt masks to protect themselves, and many cities require them in public. In Seattle, where streetcars require all riders to have masks, the local Red Cross enlists 120 workers to turn out 260,000 masks in three days.
In the 1920s, masks are standard in operating rooms.
I have a picture from a well-known hospital, taken in the 1930s. It shows a group of surgeons in the middle of a procedure.
The docs standing immediately over the operating field are wearing masks, caps, and gowns (although the famous surgeon’s mask is askew and his nose is exposed).
About three feet away from the table are a bunch of random people looking on in street clothes, including one guy smoking a cigar.