Your nose has its own immune system that works better when it is warm.
I wear a face mask when around other people in enclosed spaces. I’ve been doing that since Covid hit.
But now there’s another reason besides filtration of aerosols that could carry viruses, especially in winter. The nose is kept warm by the breath that is held in the mask.
Why Upper Respiratory Infections Are More Common in Colder Temperatures
Scientists uncover a biological explanation
By RYAN JASLOW | Mass Eye and Ear Communications, December 5, 2022
The nose is one of the first points of contact between the outside environment and inside the body, and as such, a likely entry point for disease-causing pathogens.
Pathogens are inhaled or directly deposited (such as by the hands) into the front of the nose where they work their way through the airway and into the body, infecting cells, which can lead to an upper respiratory infection. …
An innate immune response is triggered when bacteria are inhaled through the nose.
Cells in the front of the nose detect the bacteria and then release billions of tiny fluid-filled sacs called extracellular vesicles, or EVs, into the mucus to surround and attack the bacteria…The release of this EV swarm is comparable to “kicking a hornets’ nest.” … [A similar response is elicited by viruses.]… [end quote]
The quantity of EVs secreted by the nasal cells decreased by nearly 42 percent and the antiviral proteins in the EVs were also impaired when the nose temperature was lowered due to exposure to cold air. That’s a major decline in immune response.
Bottom line: Keep your nose warm! If it’s really cold, wear a scarf which will keep your nose warmer than a flimsy surgical face mask.