If there are added some sort of "danger zones" to Chernarus or any other future maps like Namalsk, either natural or as an option for server owners to set on and off, like fallout zones, areas containing deadly gases or places like that where you'd suffocate or otherwise die from hazardous causes, you would need a gas mask and/or protective gear, not just t-shirts and jeans, if you are planning to go in an area where you need the full suit.

But you'd also need a seperate filters to breath, and each mask has its own filter variant. Depending on the condition of the mask/filter, the more air and time you would have to stay in the deadly area.

The filters should spawn seperately and if you want to use them in a situation where you need the mask, you'd need to attach the filter into the mask, meaning you can detach the filter in order the mask take less space in the inventory.

For example, without the filter, the gas mask would take 2 slots vertically and with the filter on 3 slots. Also the filter should slowly become unusable (but you could still use it as means for look) in "real" situation when you use it somewhere where you need the gas mask.