With the Nilfisk Elite, you suck dirty air into the appliance, where it is filtered and exits as clean air. So you are not only cleaning your flooring, but also the air you and your family breathe. The Nilfisk Elite series has been awarded these seals of approval by the British Allergy Foundation: House Dust Mite, Cat Allergen, Dog Allergen and Pollen. When buying a hoover with a high-quality HEPA filter, you should always bear the following things in mind: The HEPA filter should be located behind the motor so that the exhaust fan emits clean air. The HEPA filter and hoover must be completely sealed so that no contaminated air can escape. Nilfisk calls this an "airtight design". A hoover with a high-quality HEPA filter is more expensive than conventional hoovers. However, it is a good investment for anyone who cares about the quality of their living environment.