Air purifiers are such a common household appliances that we feel that it applies very simple techniques. Actually it is not so. Purifiers that are really effective draw in the air from a room and send the clean purified air back to the room.
It first absorbs the air inside by using elements like activated zeolite or carbon. These medias are chosen because these are extremely porous in order to facilitate the flow of air and then expose it to a large surface. There are some chemicals in the media with which the air reacts to give out the cleansed and purified air back into the room. Absorption helps to remove tobacco smoke, chemicals and odours but it is not very effective against miniscule particles.
Mechanical filtering involves a process of screening the air inside your room. The screens that are used are extremely fine and they are able to trap particles of 0.3 micron size. This technique removes minute particles like mold spores and pollen. These screens, however, are not capable of cleaning chemicals and so it is used along with an absorption filter.
Electrostatic or electronic technology has so far been the most effective cleaner. Purifier units have charged plates that give either positive or negative polarity to particles. These charged particles get attracted to the oppositely charged plate within the purifier. The charged particles accumulate near it. When the charging voltage begins to arc it will cause a popping sound. This sound also indicates that the plates require cleaning. Purifiers also use electrostatic brushes to charge particles before being filtered mechanically. Ultra violet is another technology, which is popularly used to kill the microorganisms.
In order to give the maximum benefit to all users most high-end air purifiers use different types of pre- filters in addition to the filter elements. Pre filters help to increase the longevity of the fine filters that are within the purifier. These pre filters screen the large particles before the fine screening is done. Large particles like hair, dust and lint are found on the pre filters.
Technologies that are used are often not effective at all. These are the ones that provide ozone above safe limits. Some other purifiers use non- fan based technologies that are also not quite effective.
There have been cases when room air has been pushed back without purifying it. Manufacturers often do not state the efficiency of their purifiers and this has led to such a problem. Hence one must be careful to check and see whether the air purifiers that they are purchasing are efficient.