The ADP 70 air disinfection utilizes a proven technology commonly used in hospital HVAC systems called Photocatalytic Oxidation ( PCO). These charged ions, referred to as Hydroxyl Radicals (HO), are powerful oxidizers that destroys particles as small as .001 microns. HEPA systems only filter particles down to .300 microns. The ADP 70 continuously emits HO for on contact removal of contaminants.