Amway ATS Advanced Air Treatment Replacement Particulate Filter 2 Reduces removes up to 99.8% of airborne particulates. Filter 2 for AATS. Airborne particles are usually measured in microns. HEPA efficiency is standardized at 99.97% removal at 0.3 microns. This HEPA-like filter removes up to 99.99% of all 0.3 micron particles, depending on speed: Tested to remove up to 99.99 of particles as small as 0.01 microns.