Filters also have loading specs which seems everyone ignored. The guarantee is not that they remove x% of particles at y size, instantly, but that they settle

Filters also have loading specs which seems everyone ignored. The guarantee is not that they remove x% of particles at y size, instantly, but that they settle at that efficiency after z level of loading That also likely accounts for differences in some results - nobody seems to have taken this into accounts (There are filter rating systems where z=0, for example n95 filters. That is rare in HVAC and general air purification though)