As someone trained in non-lethal combat, pepper spray attacks the eyes and skin in addition to the nose and mouth. The difference is a liquid spray, such as an over-the-counter self defense item, versus a gaseous spray, similar to a fire extinguisher...or what the military fills the gas chamber with during training.

An N95 mask is not a defense against a motivated assailant, and any successful escape from this misfortune is due to a combination of luck and street smarts, rather than a semblance of protection.

The risks/benefits of constantly wearing masks are documented by independent medical professionals, but correlating a mask to a self defense item against a random attack is not only foolish, it is dangerous.