It is through a large wind and high pressure drop fan, the air is passed through one or several layers of filter screen to filter out the particulate matter and harmful substances. The core components are mainly HEPA (High Efficiency Air Filter) technology, which is currently the most common in the home market. According to the British BSEN specification, for particles with a diameter of 1 micron, the filtration rate should be above 85% (H10 standard, BSEN1822) can be called HEPA filter. HEPA is also divided into different grades depending on the filtration efficiency, but the difference is quite limited, and most HEPA technologies have been able to meet the needs of the family. Simply put, an air purifier without HEPA is not recommended.