High efficiency particulate arresting (HEPA) filters are designed to remove 99.97% Of all air pollutants that are as small as 0.3 Micrometers such as pollen, allergens and dust mites. For reference, 1 micrometer is 1/100th the width of a human hair. HEPA filter has much higher filter effectiveness than compared to electrostatic/ionic type air purifier and does not emit potentially harmful ozone. Activated carbon filter – also called the activated charcoal is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for absorption of airborne chemicals, gases and odor. It eliminates and removes chemical fumes, toxic gases, smoke, pet and other odors.