The NASA-founded technology is based on filterless air sanitation. However, the APS-200 PM 2.5 and the new HD line are equipped with pre-filters due to the continuous developments. As for the APS-200 PM 2.5, the goal is the more efficient protection against dust and airborne particulates. The new HD industrial products are appropriate for environments with heavily contaminated air where extreme concentration of dust, fat or pollen occurs; the pre-filter ensures the protection of the reaction chamber even under such conditions.