Air purifiers usually have 3 types of filters: pre-filers, HEPA Filters and carbon filters. 1.Pre-filters This layer of filter is basically necessary for each air purifier. It is generally made of special polyester fiber material, which looks thin and has a larger mesh port. This layer is mainly to remove hair, fiber fleece, large particles, dandruff, etc. 2.HEPA Filters It is made of laminated borosilicate microfibers, which is as thin as paper. As we can see, HEPA filters are mostly white and consist of hundreds of regular folds. A good HEPA filter generally has a filtration efficiency of 99.99% for particles with a diameter of more than 0.3 micrometers. This layer of filter can remove a variety of air pollution components like inhalable particulate matter, cigarette smoke, pollen, etc. 3.Carbon Filters The carbon filter adopts aluminum, plastic and paper honeycomb with through-hole structure as carriers. Compared with the traditional activated carbon filter, it has better aerodynamic performance, smaller bulk density, larger specific surface area, higher adsorption efficiency, and lower wind resistance coefficient. Honeycomb activated carbon filter is made of polyurethane foam with powdered activated carbon, of which carbon content is about 35%-50%. It has efficient adsorption ability, which can be used for air purification, removing volatile organic compounds formaldehyde, toluene, hydrogen sulfide, chlorobenzene and other air pollutants. This filter layer has low air resistance and low energy consumption that can deodorize and purify the environment under a certain air volume.