The hepa filter needs to be positioned post motor so as to ensure the exhaust is emitting allergen free air. For a HEPA filter in a vacuum cleaner to be effective, the vacuum cleaner must be designed so that all the air drawn into the machine is expelled through the filter
Finally, vacuum cleaner filters marketed as "HEPA-like" will typically use a filter of a similar construction to HEPA. A HEPA filter rating is applicable to any highly efficient air filter that can attain the same filter efficiency performance standards as a minimum and is equivalent to the more recent N100 rating for respirator filters. The United States Department of Energy (DOE) has specific requirements for HEPA filters in DOE regulated applications.
Products that claim to be "HEPA-type", "HEPA-like", or "99% HEPA" do not satisfy these requirements and may not have been tested in independent laboratories.
Because of the extra density of a HEPA filter, HEPA vacuum cleaners require more powerful motors to provide adequate cleaning power.
