Hygienic air is essential to human life, and in this modern age, that requires air cleaners. There are a few different methods of air cleaning, like Filtration, Electro-static Precipitation and Ion Generation. Air Filtration cleans air through the removal of sub-micron particulate, gases and odors. If you are plagued by allergies or asthma, an air filter might help you. Air filters are the best tools for eradicating allergens from the house. Particularly for those people who are suffering from asthma and allergies, both the U.S. Environmental Protection Agency (EPA) and the American Lung Association recommend air filtration.

The ability to remove allergens and contaminants depends on the amount of air drawn through the filter. Factors that affect filter efficiency include fiber size, fiber density, airflow rate, and particle diameter. Air filters may be centralized, in-home filtration systems or portable devices. When the air quality problems exist throughout the house, then a centralized filtration system is needed. Otherwise, portable cleaner may serve the purpose of air filtration.

There are four major types of air filters, depending on specific needs. They are:

Mechanical Filters
These filters force air through a special screen that traps pollen, dust particulate, smoke and air-borne irritants and pet dander. The best example of this type of filters is HEPA (High Efficiency Particulate Air) filter.

Gas Phase Filters
These air filters are used for removing odors and other types of pollutants such as gases from cooking, paints, perfume etc. These filters are not meant for the removal of allergens in the home.

Electronic Filters
In these types of filters, allergens are trapped through electrostatic precipitators with a fan. Electronic filters use electric charges to attract contaminants.

Hybrid Filters
These air filters combine electrostatic and mechanical filters. These are used to trap allergens rather than gas based contaminants.

Another type of air filters is the Ozone air filter, but it is not environment-friendly.

When purchasing an air filter, one has to consider things like which type of allergens will be removed, the filters efficiency with respect to HEPA standards, the clean air delivery rate (CADR) of the filter, the ease of changing the filter, and the noise that it will make. Changing air filters regularly facilitates is ability to improve the quality of air.