Comment by stephen_g

So? We're talking about practical effectiveness here. The difference really only matters if you only have one chance to filter the air, like the filter in a ventilation system bringing air into a cleanroom (the article goes into this).

Since the air purifier intakes and exhausts in the same space (meaning filtered air gets re-filtered), all the slightly worse filter means it that you'd need to run it for a couple more minutes to get the room down to a similar concentration of particulate per unit volume... So the difference in particulate concentration would likely not be anywhere near 10x at steady state, it would be much smaller (but depends how much air leaks into the room from outside, the particulate content of the outside air, the volume of air you're getting through the purifier per unit time, etc.)