I really don't think Mark would want to take his helmet off regardless - he's in the same cell as a wounded, pissed off Mishhu that's charging him. XD
Regardless though, the character never was specified as having which model from the company. Not only that, but knowing that there's something in the air, I would have thought he would be adverse to breathing in the gas, especially given his history. Hell, I thought he'd be rather phobic to the situation, but that's up to you ultimately.