Air Filters

Air Filters are specially designed devices used to  purify the air we breath. They have the ability to capture and remove pollen, smoke, toxins, irritants and other allergy causing particles in the air. They are placed in air purifier  or air cleaner units.

An Air Filter is positioned in the air purifier unit in a manner that allows it to remove particles from the air that passes through it. It is part of the cooling and heating systems of houses. Most of the time it’s installed between the furnace and the return duct of the system.

This is done for two main reasons.  Firstly, this arrangement helps the air filter to decontaminate the air passing through the furnace. And secondly the air filter greatly reduces  damage to the  furnace by preventing dirt and dust accumulation on the furnace.

The efficiency of an air filter is partly determined by the density of the air filter.  Lightly densed filters captures and removes only large size of particles as the size in these filters are large. They hardly catch very small and tiny particles. But a very dense filter can catch very very tiny particles. The gaps between densed filters are very small. And this makes them effective in removing small particles in the air that passes through them.


Some filters are pleated. This is done to increase and widen thier surface areas. Pleating helps air filters to remove more particles and contaminants from the air passing through them.


We have different sorts of air filters. Each type of an air filter purifies air in a unique manner. Let’s briefly look at the common type of air filters we have.

HEPA ( High Efficiency Particulate Air) filters are the most well known air filters. They are also the most efficient. They allow only 0.03 percent of the particles in the air passing through it to penetrate. This means it removes almost 99.97 percent of contaminants. This is an incredibly high rate. It can catch particles as tiny as 0.3 microns.


We also have IONIZING PURIFIERS.  These purifiers use small but intensed electrical fields called CARONA DISCHARGE to charge molecules in the air passing through it. Most of the particles in the air have no charges. They are neutral. Making them unattractive to charged poles.

Ionizing Purifiers charge large molecules in the air. And once they are charged,  they are attracted and captured by the charged plates in the unit. Oppositely charged molecules can clump together and fall out of the air.


Some air cleaners (Note : Air cleaners and air purifiers are used interchangeably) have ADSORBENT MATERIALS installed in them. These materials remove chemicals, fumes and odor in indoor air. They are many adsorbent materials available. The most common one is ACTIVATED CHARCOAL.  some particles go into reaction with charcoal and are captured this way. Other particles simply get trapped in the pores of the charcoal.


These air purifiers are like the ionizing air purifiers we discussed earlier. Just that they create large quantities of Ozone. You wouldn’t want to use these unite especially if you are an asthmatic patient. OZONE is quite dangerous and harmful. It causes respiratory problems. Especially bronchospasm. Ozone also reacts with other compounds to produce more dangerous substances.


Air purifiers with UV LIGHTS.

These air purifiers eliminates disease and illness causing organisms in the air. They will especially viruses and bacteria.

I hope this piece was enough to give you an idea as to what air filters are and what they do. Feel free to leave us a suggestion, comment or question if you have any.