Hoover Air Purifier 400, WH10400 Ti02 Coated Screen - The Titanium Dioxide coated screen boosts UV effectiveness by helping to remove 99.9% of germs passing through it under UV light UV Bulb helps remove airborne germs, bacteria, and other microorganisms when exposed to the short ultra-violet wavelengths UV/Ti02 on/off controls are for use during flu season and can also be used all year round. Turn it on to help remove bacteria and germs from air passing through the screen under UV light Rinsable Pre-filter is the first line of defense in the multi-stage filtration system to catch lint, pet hair, and other large particle so the HEPA filter can do its job by capturing the smallest particles Has a large porous charcoal filter layer that absorbs airborne odors