So gas masks obfuscating vision?
Sounds fine with me. I mean I have to wear a gas mask frequently IRL due to my job and I can tell you... its not a pleasant experience at all. While its not making you nearly blind it severly reduces your perception you have. Its like you have a much more narrow field of view. And the harder it is for you to breath when wearing one the harder it is for you to see. Also... lets talk about filters... IRL gas masks have filters... some filters are even highly specialized for certain envirements. For instance there are filters for biological hazards and filters for corrosives (Acid and Base Vapors, Mustard Gas etc). And then there are filters for toxins (Sarin, Tabun, HCN, HF (which is also fairly corrosive)). Heck we even have a specialized filter for Mercury compounds...
Anyways depending what filter you use you either have less trouble breathing through the mask or more. The filters for neurotoxins for instance are in particular very nasty and hard to breath through. So if possible we could make the vision you loose when wearing a mask depending on the filter catridge being used (I think thats called sensory dulling). Also you would need to swap catridges depending on the situation. That means in terms that breath masks wont protect you (fully) from vapors, giving people a reason to put on a mask if a threat is there. Also Traitors (or shitters) could remove the filter catridge to only loose a little bit of their vision and insert it when its required.
One last thing I experience personally whenever wearing a mask, some other people do too... when you wear one your hearing sense is impaired aswell in some way, probably has to do with the fact that your most important senses (vision and smelling) are severly hindered. Some people turn deafer when wearing a mask, some people get very sensitive to sounds. Really depends on the person.