if mask is + pressured by remote air supply, is this safe ?

I am exploring the best combination of remote supplied filtered air + mask setup regarding:

If a mask has a NIOSH certified remote air supply creating a positive pressure inside the welder's mask, is he 'safe' ?

If maybe, does this depend on the amount of positive pressure, and if yes, how much and how can you be certain this minimum standard is met ?

I should add that I am motivated in this by assuming other used for this setup, for example, possibly working with fiberglass or painting, with a clear lens in the mask, of course.

Appreciatively,

Courtney