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The rapid development of air filters is closely related to the development of military industry and electronic industry. In the first world war, the use of various chemical agents, asbestos fibre filter paper as the smoke filter layer of military gas masks came into being. The glass fiber filter medium is used in air filtration to obtain a patent in the United States in October 1940. In the 1950s, the United States studied the production process of glass fiber filter paper, and the air filter was improved and developed. In the 1960s, HEPA filters came out; In the 1970s, the filter paper of fine glass fiber was used as the HEPA filter of filter medium, and the filtration efficiency of particle size of 013 micron particle diameter was 99.9998%. Since the eighty s, with the emergence of new test method, use evaluation to improve and to improve the filtering performance requirements, found the HEPA filter there is a serious problem, and he had a higher ULPA filter performance. Countries are still working on it and expect more advanced air filters soon
California houses some of the biggest Hollywood stars and professional sport teams like the San Francisco 49ers (NFL), Los Angeles Kings (NHL) and of course the Los Angeles Lakers (NBA) who won their 16th NBA Finals this season by defeating the Boston Celtics (Lakers won 4 games -Boston won 3 games). The Los Angeles Lakers doesn’t always win finals consecutively but what’s appear to be consecutive is the riots in California’s jails and prisons, especially Folsom State Prison.
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