Our top-of-the line filter captures 99.97% of airborne particles as small as 0.3 microns from the air passing through the filter media (based on Initial Efficiency Value) including dust, allergens, bacteria and viruses. Designed with electrostatic air filtration, the Filtrete™ Premium True HEPA Filter traps particles 1000x smaller than the human eye can see. Say hello to cleaner, fresher indoor air.