What does air purifier h7 and h12 mean?

Referring to the level of the filter, the higher the level of the EPA net, the smaller the diameter of the particles that can be filtered, the better the filtration effect. At present, the ordinary air purifier on the market is H10H9 level of HEPA net, high-end air purifiers are generally used in the H12 level of HEPA net, a very small number of high-end air purifiers using H13 level of HEPA net, H13 level of HEPA net is the top imported medical-grade Cleansing Soft HEPA filters, filtering effect is the best. The best filtering effect. Therefore, at least you should choose the air purifier with HEPA mesh level above H12, and try to choose the air purifier with H13 level HEPA mesh if you have the condition. Currently on the market with this level of air purifier, as far as I know there are three dad brand.