Emergancy Filters for Gasmasks?

[Roomba]

I'm not entirely certain on the mechanics of what you're asking for. I guess it's a filter that straps on to gas masks and contains a little bit of breathable air? A gas mask already does the job of filtering out harmful smoke/gases, it's just that without a source of breathable air from a tank you won't be able to breathe regardless. I don't really see how a filter can contain air, though. I feel like your one question relies on a whole lot of other implicit questions that should probably be answered first.