EN 1822-1:2009 has been prepared by Technical Committee CEN/TC 195 "Air filters for general air cleaning", the secretariat of which is held by UNI. It supersedes EN 1822-1:1998. The national interests during the preparation of the standard were represented by the Mechanical Engineering Standards Committee (NAM), Technical Section General Ventilation, at DIN. Representatives of the interested parties, amongst them manufacturers of high efficiency air filters, users, and research and test institutes were involved in the preparation of this standard. The EN 1822 standard series "High efficiency air filters (EPA, HEPA and ULPA)" deals with the filtration performance testing of efficient particulate air filters (EPA), high efficiency particulate air filters (HEPA) and ultra low penetration air filters (ULPA) at the manufacturer's site and consists of the following parts: Part 1: Classification, performance testing, marking Part 2: Aerosol production, measuring equipment, particle counting statistics Part 3: Testing flat sheet filter media Part 4: Determining leakage of filter elements (scan method) Part 5: Determining the efficiency of filter elements The standard is based on particle counting methods which most likely cover the requirements of different applications. The differences between this European Standard and the previous standard are as follows: * an alternative test method using a solid (instead of a liquid) test aerosol; * a method for testing and classification of filters made out of membrane type filter media; * a method for testing and classification of filters made out of synthetic fibre media; and * an alternative method for leak testing of group H filters with other than panel shape. Beside that, various editorial corrections have been implemented. As decided by CEN/TC 195, this standard is based on particle counting methods, which actually cover most requirements of different applications. The difference to previous standards lies in the technique used for the determination of the integral efficiency. Instead of mass relationships, the new technique is based on methods for particle counting at the most penetrating particle size (MPPS), which is for micro-glass filter mediums usually in the range of 0,12 µm to 0,25 µm. For membrane filter media, separate rules apply which are included in Annex A of EN 1822-5. This method also allows for testing ultra low penetration air filters. This was not possible with the previous test methods because of their inadequate sensitivity. DIN EN 1822-1 applies to high efficiency particulate and ultra low penetration air filters (EPA, HEPA and ULPA) used in the field of ventilation and air conditioning and for technical processes, for example, for applications in clean room technology or pharmaceutical industry. It specifies a procedure for the determination of the efficiency on the basis of a particulate counting method using a liquid (or alternatively a solid) test aerosol, and allows a standardized classification of these filters in terms of their efficiency, both integral and local.