The Dyson Airblade™ hand dryer's HEPA filter captures 99.97% from the washroom air. So hands are dried with cleaner air. Antimicrobial coating and touch-free operation helps to prevent the spread of bacteria. So Dyson Airblade™ hand dryers meet every part of NSF Protocol 335, which defines the criteria for hygienic hand dryers. Purchase comes with two replacement filters, one for each side of the unit.