Choosing the best HEPA ionizer to purify indoor air requires some research to gain familiarity with this type of air purifier. Sometimes called "combination" purifiers, these units combine a high-efficiency particulate air (HEPA) filter with ionizing technology. Knowing how large an area will need air filtration is another prerequisite to deciding which HEPA ionizer will be the best choice. Consumers should look for a rating by the Association of Home Appliance Manufacturers (AHAM) as well, and compare the testing results for each model under consideration.
Combination-style HEPA ionizers claim to deliver the best of both worlds when it comes to air purification. The ionization feature produces electrons that bind to molecules in the air, forming negative ions. These ions then attach themselves to particulate matter in the air, which either clumps together and falls onto room surfaces for cleaning or attaches to the unit's grill. The addition of HEPA filters help trap these particles, as well as smaller ones that may be missed by ionization alone.
Consumers want these HEPA ionizers because they are believed to be more effective in removing pollutants from indoor air than other style air purifiers. Persons with allergies, asthma or other respiratory disorders will often use these devices to remove allergens and other irritants from indoor air. Some believe negative ions themselves are beneficial, while others just want to reduce indoor pollution for general health reasons.
When researching HEPA ionizers, it is important to keep in mind the size of the room for which the purifier is intended. There are also whole-house units, which are understandably more expensive than room-size devices. One should also keep in mind, particularly if health issues are part of the reason for the unit's purchase, that a HEPA ionizer may emit ozone, which is considered a lung irritant. Clean HEPA filters are necessary for optimum performance, so the life expectancy and cost of replacement filters should be compared, too.
When comparing HEPA ionizer units, consumers should check to see whether the product has been tested by AHAM using its clean air delivery rate (CADR) system. The higher the CADR score, the better the purifier performs, and these numbers can be useful when units are compared against each other. Not all HEPA ionizer air purifiers are tested by AHAM, so reading user reviews on the Internet can be a useful research tool. Many retail sites that sell these products invite consumers to comment on and sometimes rate them, affording invaluable insights into how these products perform under everyday conditions.