... Particulate Air2) These filters are designed to remove up to 99.97% of airborne pollutants, at 0.3 microns or larger, from ... include tobacco smoke, household dust, pet dander and pollen 4) 99.97% HEPA filters typically need to be replaced every 12 – 18 ... months for best performance 5) 99% HEPA filters typically need to be replaced every 4 – 6 ...