Better question:
Why in the world are they wearing them? I have seen them at con's before and the first thing that comes to mind is that they are retarded. To prove this, I asked a number of different furs at conventions why they were wearing a gas mask. not one of them could tell me why! one answered "I was told to" another answered "I don't know" yet others pointed and shook their heads like they couldn't talk.
If there are other reasons, I'd love to know.