is important and the load in fine particle quite important. Filters can also be placed at any point of air exchange in the process to avoid that pollutants enter the process, which is particularly true in pharmaceuticals and food industries. The physical phenomena involved in catching particles with a filter are mainly inertial and diffusional Filter classes Under European normalization standards EN 779, the following filter classes were recognized: European standard EN 779, on which the above table is based, remained in effect from 2012 to mid-2018, when it was replaced by ISO 16890. See also Air purifier Clean Air Delivery Rate Cyclonic separation Diesel particulate filter Dust collector Corsi–Rosenthal Box Impingement filter Mechanical filter (respirator)#Filtration standards Nose filter Oil filter Respirator Scrubber Smog tower Swan neck duct References External links Auto parts Air filters Particulate control Engine components Gas technologies Solid-gas separation ja:エアクリーナー