I don't know the answer to that. But there's a pretty good chance the dust would get deflected in the boundary layer. The more problematic part is when you got

I don't know the answer to that. But there's a pretty good chance the dust would get deflected in the boundary layer. The more problematic part is when you got to the orbit and there is no more air to form this boundary layer, and specks of dust will hit the balloon directly. I suspect that the microscopic holes that they form will let some of the gas out, but not enough to make a difference.