This highly effective air purifier captures 99.97% of the microscopic particles (0.3 microns and larger) that pass through its filter.Honeywell True HEPA air purifiers are efficient at capturing airborne pollutants like dust, pollen, pet dander, mold spores, and tobacco, cooking and fireplace smoke particles.This model also captures certain bacteria and virus from the air passing through the filters. With a slim design and easy-to-use controls, this air purifier uses a mechanical filtration process, meaning that a fan pulls the particle-filled air into the unit and forces that air through a HEPA filter, effectively cleaning and circulating the air in the room up to five times an hour. And, Honeywell True HEPA Air Purifiers do not release ozone back into the air from the filtration process, making them the preferred option of Allergists.