SPT Hepa Air Purifier with Ion Flow Technology, White Activated carbon filter: helps remove household odors Anti-bacterial pre-filter: first stage of capturing and removing bacteria and microorganisms Hepa filter: a high-efficiency air filter that captures 99-1/2-percent of airborne pollutant particles as small as 0.3 microns, including spores, pollen, mold, pet dander and dust. Uv light: sterilizes the air by breaking down microorganisms, such as germs, viruses, bacteria, fungi, mold, etc; effectively destroys the nucleic acids in these microorganisms so their dna is disrupted and destroyed; ion flow Tio2 (titanium oxide) filter + uv: photo catalytic oxidation is achieved when uv ray combines with a tio2-coated filter; this process creates hydroxyl radicals and super-oxide ions, which are highly reactive electrons