The Holmes Desktop Air Purifier with HEPA-Type filter captures particles as small as 2 microns and operates quietly to remove up to 99% of airborne particles such as pollen, dust, mold, pet dander, and smoke, providing relief from odor and irritants in the air so you can breathe comfortably. The optional ionizer ensures particles are more easily captured while also tackling odors. The Holmes small desktop air purifier can be placed vertically or horizontally and is designed to fit just about anywhere and effectively treat the air around you.