Air purifiers convert dirty air into fresh and clean air, and also free the air from pollutants and contaminants. They are very beneficial for people suffering from allergies and can help alleviate asthma. Allergy inducing particles within the air may come as dust, pollen, pet dander or mold spores.

There are numerous air purifier brands and manufacturers worldwide. It becomes too tough for a customer to pick the air purifier of one's choice from the huge range available.

The best idea is to do some research online. Thanks to the online reviewers, there are some good air purifier comparisons and reviews on the Internet.

A decent air purifier review will honestly depict the pros and cons of a specific air purifier. Therefore, going through numerous air purifier reviews will help you make a good decision before buying an air purifier.

There are a large number of air purifiers including Oreck Super Air 8, Sharper Image Ionic Breeze GP, Friedrich C-90A, Sharper Image Ionic Breeze Quadra, Blueair 601, Bionaire BAP1300 Quietech HEPA, Honeywell HEPA 50250, Hunter Quietflo 30400, Vornado AQ535, Hunter HEPAtech 30375 etc.

Oreck Super Air 8 is a good quiet machine, quite effective at clearing the air of a number of pollutants, allergens, and irritants. It's efficient, covers a large area and quite inexpensive having a strong warranty.

Sharper Image Ionic Breeze GP is a good home air purifier having a germicidal UV lamp. Ultraviolet radiation is capable of combating many pathogens such as viruses and bacteria. It's quiet and quite effective in air purification, with a 5-year warranty. The Asthma and Allergy Foundation of America awarded it with a Consumer Product seal as its "proven to reduce airborne allergens and irritants including dust mite allergen, pet dander and cigarette smoke".

Friedrich C-90A is good, efficient but a little noisy and bit costly also. Sharper Image Ionic Breeze Quadra is also good at removing pollutants and the Asthma and Allergy Foundation of America also awarded it with a Consumer Product seal.

Blueair 601 using activated carbon technology is particularly effective in removing odors and gases. It's considerably cheap with 10 Year Overall Warranty.

Bionaire BAP1300 Quietech HEPA is a powerful air purifier, a bit noisy and requires a regular filter change. It has a 5-year warranty.

Honeywell HEPA 50250 is good and effective in small rooms. Its price line is good with a 5-year warranty. Hunter HEPAtech 30375 is a good device having an ionizer that can be controlled independently.

Recently, there has been a controversy that ionizing air purifiers produce ozone (O3 poisonous allotrope of oxygen) that can worsen asthma and decrease lung function. Some critics feel that air purifiers are over hyped devices that can't completely clean the air and protect against secondhand smoke.