The purification of air purifiers should be divided into three categories based on their working principles: The first category: passive purification (filter purification). The main principle is: use a fan to draw air into the machine. The air is filtered through the built-in filter, which can mainly filter dust, odors, toxic gases and kill some bacteria. Filters are divided into: dust collection filter, formaldehyde removal filter, deodorizing filter, HEPA filter, etc. Among them, the more expensive one is the HEPA filter, which can decompose toxic gases and sterilize, especially to inhibit secondary pollution. The characteristic of this type of product is that the fan function and the quality of the filter determine the purification effect. The placement of the machine and the indoor layout affect whether the purification is complete. The indoor purification effect is uneven and difficult to complete, and the filter replacement cost is high. Product representatives: Honeywell and other European brands. The second category: active purification type (no filter type). According to the active sterilization principle of these products, they can be divided into silver ion technology, negative ion technology, low-temperature plasma technology, photocatalyst technology and pure ion cluster ion technology. The first generation, silver ion purification technology. Simply put, it is to ionize silver blocks and blow them into the air to achieve a sterilizing effect. The disadvantages are high product cost, low bacterial killing rate, and almost no killing properties against viruses. Product Representative: Early Panasonic products. Second generation, negative ion technology. The main principle is to use static electricity to release negative ions, which absorb and concentrate dust in the air to reduce dust. At the same time, negative ions also ionize oxygen in the air into ozone, which has a certain killing effect on bacteria. The advantage of this type of product is the production cost. lower. Product representatives: Yadu, Philips. The third generation, low temperature plasma technology. The main principle is that by applying an external voltage to the gas to the discharge voltage of the gas, the gas is broken down, generating various strong oxidizing low-temperature plasmas, and decomposing the pollutants in contact in a very short time. This technology is generally used for industrial waste gas treatment. Secondary pollution is produced after chemical reactions. If it is applied to household air purifiers, human safety testing and corresponding secondary pollution treatment technology are required. The fourth generation, photocatalyst technology. Photocatalyst is actually a technology that uses semiconductors to release free radicals with strong oxidizing power under the irradiation of light. The advantage of this technology is that the product cost is low, but the disadvantage is that the free radical activity causes it to stay in the air for a short time, and its killing effect on viruses and bacteria is also limited. Product Representative: Daikin. The fifth generation, plasma cluster technology. Sharp's 2000 global patented technology. It is a technology that directly ionizes water molecules in the air into H radicals and OH radicals, and then wraps the water molecules. The killing rate of OH free radicals against viruses and bacteria exceeds that of ozone, and it also stays in the air longer than ozone. Plasma cluster ion technology wraps OH radicals with a layer of water molecules to keep them in the air for a long time. At the same time, it uses the water-draining properties of bacteria and viruses to kill bacteria and viruses more quickly. This technology is currently an internationally recognized medical space purification technology, and it is currently the only space purification technology that can kill H1N1, H1N5 avian influenza, and SARS with a killing rate of more than 99%. Product Representative: Sharp. The third category: dual purification type (active purification and passive purification). The main representative brands of this type of purifier are: (1) Sharp (filter ion cluster technology); (2) Blueair (filter negative ion technology); ( 3) Philips (filter negative ion technology). Here is the brief content, you can check out the details on the Sharp air purifier website