Careful though. Those things can destroy your hvac system, which is not designed to deal with a severe restriction like that. Plus, they won’t last long with no pre-filtering at all. Shame to have a great filter like that just clog up with hair and pollen in three weeks.

If you're recirculating the air through the filter many times, the capture rate doesn't really matter. What you don't catch on the first pass you'll catch in the 2nd.

From that point of view, even a 90% catch rate sounds fine.

When you're dealing with a machine that is exchanging air in a room a certain number of times per hour and a continuous influx of particulates, with less efficient filters you need more air exchanges which means more filters, bigger fans, etc.

The takeaway is that less particle efficient filters won't ever get you down to the same steady state as better filters in real world applications.

And from personal experience with filters and devices to measure airborne particles, it is hard enough getting good numbers with the best filters I can find.