QuoteI wouldn't fully discount it, but it seems unlikely that this dust would accumulate right around the cell in a more concentrated manner than it would be otherwise in the immediate environment. Should be easy enough to rule out with further testing.
It would not - but convection currents can alter dust content in air. In any case that was one mechanism. There are others, and the best way to show this is something about the experiment is to run a control which is physically as identical as possible to the original but with no active material.