OMG! N95 masks are designed to help prevent the SPREAD of virus, not CATCHING it. Read on the package, it says for EXHILATION filter, not INHILATION. Respirators, which cost 5x more, are designed to protect from toxic fumes such as for painters, and will stop coronavirus. https://globalintelhub.com/survival-guide-coronavirus-2020-pandemic/
Exactly seeing someone with a surgical mask it is to assume he/she is infected (or is a surgeon in a operating room).
Something as small as 125nm requires a gas-mask with eye-cover.
Vitamin C is extremely important and your body looses a lot of it with stress. The body can not store large amounts of Vitamin C and it can not prevent infections, but help enormously if infected.