Air filters are generally used to remove dust particles and other minute unseen particles like pollens and bacteria from the air. They are mainly used in devices where the purity of air is the major factor of operation, such as, ventilation systems, combustion engines, compressors, turbines and the air conditioners.

The air is required to be pure and without dust in places like research laboratories where even a dust of 1ppm or 1 part per million could contaminate the environment and would cause a lot of effect in the research recordings.

House air filters are very necessary in hospitals where patients suffering from wheezing and asthma have to be in a very pure environment free of dust, else their problem could aggravate.

Even in a house where there are babies or old people, care should be taken that they breathe air free of dust to the maximum extent. House air filters and air purifiers can help in this regard. my site http://www.chinafiltercloth.com/

Things like foam, ruffled paper, fiber glasses are used as air filters. Even fibers and elements that have static electric charge are used as air filters. The internal combustion engine uses filters like paper or cotton.

There are four major types of air filtering medias - they are the paper, foam, synthetic and cotton fabrics. These filters should be serviced regularly and the dirt should be removed regularly so that they work better in the long run.

There are also HVAC (Heating, ventilating and air conditioning) filters available and are manufactured using the fiber glass technology. They are very cost effective and also disposable. There are Universal Air Filters also known as the UAF that are used for filtering the air.