They shoved herbs in their breathing hose because they knew the air was bad and hoped it would help, and *they were right* in theory. The plague itself was not an airborn virus, but they couldn’t know that and it wasn’t the only thing killing people at the time anyway, and they covered *all* their bases. If they’d had the technological knowhow to make air tanks, or even better air filters, they would’ve. They just made the best air filters they could.
What we think they wore isn’t exactly what they wore, and what they actually wore would later be repurposed into scuba suits (and thus spacesuits too) and *actual hazmat suits*, because the theory was sound, the materials were just lacking, and honestly what they did with the materials they had was hardcore.
they wore full face protection which avoids the most obvious mucosal transmission routes
INCLUDING GLASS IN THE EYEHOLES. They invented safety goggles before most of the world had nailed down corrective eye glasses yet
they wore additional head protection to cover seams in their mask/hoods
they oiled and waxed all their clothes to make it fluid-resistant
they wore separate but tight fitting equally if not more fluid-resistant gloves and/or armcuffs so they could keep hand contamination to a minimum even when dressing/undressing AND they only wore the suit in areas they thought was contaminated and took it off before entering uncontaminated areas
they may have used herbed vinegar to clean, and if the stories are true this was clever because 1) it’s available and portable 2) pretty effective as far as medieval disinfectants go versus the damage it does the the user (as opposed to what they had for bleach at the time, and the actual percentage level in alcohols at the time which was mostly insufficient for task as well as being needed for more important things); vinegar is *still* a decent disinfectant even now
It honestly took doctors well into the twentieth century to get that level of obsessive attention to hygiene and cross-contamination back. A whole lot of babies and mothers wouldn’t’ve died, for instance, if a plague doctor instead of an obstetrician supported the birth because A PLAGUE DOCTOR WOULD KNOW TO WASH THEIR GODDAMNED HANDS.
Actual plague doctor’s outfits:
