Quote:
40 microns? Isn't that fairly big; like a boulder?
Close!
An almost unseen boulder. From
this link.
Micron size of family particles
Grain of table salt........100um
Human hair .................80um
Lower limit of visibility....40um
White blood cell............25um
Talcum powder..............10um
Bacteria....................2um
As for the OP's question, it could well be that 3323 BD+ is similar to the P1. But, as pointed out the BD+ is a different filter with differnt media than the P1, so perhaps not.
But, ZeeOSix has noted in the past that, 99.9% @40um could still be ~95+% @20um.
But at this point, afaik there is no definite answer.