Why would you use a HEPA air purifier? High efficiency particulate air [filter] is the name of the acronym (as officially defined by the U.S. Dept. of Energy). Theoretically, this kind of air filter can eliminate 99.97 percent or more of dust, pollen, mold, germs, and any other airborne particles smaller than 0.3 microns (m). What distinguishes an air purifier from a HEPA filter? Conclusion. Filter-free, economical, and silent, ionic air purifiers are ideal. The tiniest dust and pollution particles, as well as smells, are particularly well-removed by HEPA filters. You will profit from the advantages of cleaner, fresher air either way. Are HEPA air cleaners superior? Pet dander, pollen, and dust mites are examples of bigger particulates that HEPA is effective at eliminating. Unfortunately, a HEPA-based air purifier cannot safely remove microscopic particles smaller than 0.3 micrometers, viruses, germs, or mold from the air.