No scientific tests have been made there. Clearly it makes under pressure inside the enclosure, meaning that particles won't go out from intake holes or some other holes in enclosure, but through the filter. On the other side of the filter there is no smell and no dust, while I can clearly see both filters quite dirty after all that time of usage. (I replace carbon filter every 1-2 months, and HEPA every 6 months or so). Maybe that comment would be better inside a HEPA+Carbon filter Thing.