The Honeywell HEPAClean Tower Air Purifier utilizes a long lasting filter that is rated an impressive 99% in the capturing of airborne particles such as smoke, dust, pollen, pet dander and mold spores from the air that passes through the filter. This air purifier operates very quietly while simultaneously changing the air in the room up to every 12 minutes. An especially handy Electronic Filter Clean Indicator shines and illuminates to remind you when to clean the filters. Increasing the air freshening experience to an even greater extent, an ionizer can be utilized and switched on or off at command. The sleek and slim design of this unit makes it an ideal selection for any room in your home. 3 distinct air cleaning levels have also been implemented for maximum air cleaning efficiency. The overall particle reduction is dependent on many factors. These include the amount of air processed, pollutant type and pollutants introduction rate. It is recommended that the HHT-090's HEPA filter be replaced every six months, while the pre-filter be changed every three months.