Not surgical masks. They don't offer any protection from tear gas or pepper spray. In fact, any irritant that got under the mask would create an even bigger problem, because most of these irritants are stimulated by body heat, and it's warmer under that mask than your skin that's exposed to air. We had yearly training in CS and CN gas use. You were advised if you wore contacts, to take them out before being exposed to the gas, because it can get under the contacts and burn or blister. If you were exposed to gas, you were told to keep your eyes open and let them tear, and that is very hard to do, despite the fact that you know it should be done. We were told not to rub our eyes, but that's the first thing you want to do. Flushing the eyes with water helps, but it doesn't get rid of it totally, and your clothes absorbed the stuff, and if you didn't remove your clothing, and get rid of it, those gas particles on your clothing could start the effect all over again.
those gas particles on your clothing could start the effect all over again.
Not actually a gas, a micro pulverized solid.
Different methods used for dispersal.
The particles get in the fiber of your clothing, hair, eyebrows...