Permanently charged Electret filter effectively captures 99.97% of particles as small as 0.1 micron in size from the air that passes through the filter. The HEPAtech filter has 3 different filters that the air is strained through. *Filter 1 is a Pre-filter - It removes large dust particles, lint, and hair from the dirty air. *Filter 2 is the Sub-Micron Filter - It captures 99.9 % of all airborne particles as small as .1 microns from the air. *Filter 3 is the Activated Charcoal Filter - It absorbs and help eliminate cooking odors, musty air, tobacco odors and pet related odors as it freshens the air.