Tungsten is a wolfy that cannot be affected by radiation and biological or pathological threads, such as virus, bacteria, fungi, protozoa, etc. That gas mask is part of him, it can't be removed, it's unknown how he ended up like that and he doesn't talk.

I love him so much, I've been meaning to make radioactive my 'sona but I didn't think that would work, I thought it would be much better to create a another chara and finally came up with something I really liked. This is a temporary ref cause I'm not sure if this is going to be his final design, I wanted to give him body markings but didn't like the ones I tried, so we'll see. Also, thanks to my dad I gave him that name, so kudos to him for being such a nerd haha