Ionic air purifiers
An air ioniser is a relatively new device. Ionic air purifiers do not have a cloth filter like the HEPA machines and work by ionising the air, causing particulates to gain a positive or negative charge.
The air ioniser has collection plates that have an opposite charge from the particles in the air, so the particles are drawn to the collection plates. The particles can also be attracted to other particles that have an opposite charge. This causes the two particles with opposite charges to stick together and fall out of the air.
An ion is a particle that has a charge, either negative or positive. The purifier creates negative ions using electricity. These ions seek positively charged particles, such as dust, dander, bacteria, pollen, mould, smoke, chemical vapours, and many other allergens. The particles, once bonded, are too heavy to float and as a result, the harmful suspended particles settle down and can be removed by normal means.
An air ioniser creates ozone when negative ions are generated. This controls pollution by breaking it down into smaller, harmless components. Ozone helps control germs, and deodorizes as well.
Also, scientists believe that when charged particles aggregate together and fall out of the air, this leads to disinfecting of the atmosphere and hence stopping of the transmission of communicable diseases. Ionic wind helps to circulate air in the room and is also believed to be a part of the process. A ionised fluid stream, caused by a strong electric field is known as ion wind or ionic wind.
One kind of air ionisers creates small amounts of ozone, which is claimed to be relatively harmless to humans even as it is highly toxic to air-borne bacteria, and destroys these infectious organisms when they come into close contact it.
The other type of ionic air purifier cleans air by generating negative ions. These are attracted to positively charged dust and smoke particles and the new heavier combined particles then fall out of the air, leaving it purified.
Unlike fan-driven air purifiers, ionic air purifier conserve power and run silently. Also, because there are no physical filters no parts need regular replacement, which is another advantage over other purifiers. The ionisation creates a faint breeze that helps to distribute the ions throughout a room, even though most air ionisers do not have a motorized fan. To catch the particles of dust as they fall to the ground, some also have screens or prongs.
Three Types of Ionic Air Purifier
On the basis of techniques of cleaning there are three different types of Ionic air purifiers. The purifiers are in the form of: Electrostatic Precipitator, Negative Ioniser and Media-Charged Filter.
As they come into the purifier, electrostatic precipitators give particles a negative charge. In order to attract the particles, these have positively charged metal plates. To remove the particles, the plates have to be cleaned.
Positively charged ions such as dust, fumes and smoke are cleaned by negative ionisers. They settle down on the ground, from where these can be vacuumed.
Media Charged Filters have a charged filter that has a charge opposite to the ions and hence collects the particles. It tends to lose its efficiency quickly, however, and needs to be replaced frequently.
Ionic Air Purifiers and Ozone
Ionic air purifiers produce ozone, which has an unpleasant smell at first. Unlike the Negative Ionisers, Electrostatic Precipitators and Media Charged Filter produce less ozone and clean the particles out of the air instead of causing them to stick on the floor.
While cleaning viruses, bacteria, smoke and fumes that circulate through the room, ionic air purifiers effectively remove all types of particles from the air. These also capture allergens such as pet dander and dust mites.
However, according to ‘Consumer Reports’ (CU), a non-profit product-testing magazine based in the United States, air ionisers do not perform to high enough standards as compared to conventional HEPA air filters.
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