Air purifiers are an excellent tool for eliminating indoor odors and reducing allergens. Simply put, an air filter captures pollutants and expels clean air, much like a tree absorbs carbon dioxide and releases oxygen. However, just like trees, the types of filters are legion. Carbon prefilters capture hair and some odors; volatile organic compound (VOC) filters trap odors and airborne pathogens; and HEPA filters reduce indoor allergens such as dust and pollen. However, air filters are only the tip of the purification iceberg. Some air purifiers use ionizers and UV light, but you may not know what these technologies actually do. This article will give you simplified explanations and warn you about the potential dangers of both. We do not want to scare you away from air purifiers that use ionizers and UV lights, but we do want you to understand the risks and be careful when you use them. Many of the air purifiers that we reviewed include an optional ionizer. In fact, some of our favorite purifiers use ionizers to increase the cleaning power.

But what does this technology do? Without confusing you with too much chemistry, oxygen is a neutral element that loves to change its charge. An ionizer uses an electromagnetic charge to add or remove electrons from oxygen atoms, making the oxygen particles either positively or negatively charged as they leave the ionizer. Ionized particles are far more common in the upper atmosphere, and the air we breathe tends to combine oxygen molecules with several other elements. In theory, after the oxygen passes through the air filter, it detaches from other particles and looks for a new particle to bond with. The ionizer gives the outgoing air an electromagnetic charge so that it will bond with other particles more easily. Then, when the charged ion passes through the air filter a second time, it is easier to capture. The potential danger with this is that humans don't usually breathe ionized air, and many studies show that electromagnetically charged particles can damage lungs. Also, if an oxygen molecule bonds with two others, it becomes O3, or ozone.

Ozone can irritate airways and exacerbate breathing-related problems. The best way to use an ionizer is with an operation scheduler or timer. This way, you can run your air purifier and ionizer while you are out of the house. Then, the charged particles will bond with other compounds without damaging your lungs. However, if you are sensitive to ozone, you should avoid ionizers entirely. When an air purifier uses a UV light, it promises to eliminate airborne pathogens. Many point to the UV light hospitals use to purify equipment. In theory, ultraviolet rays will kill the microorganisms passing through your air filter. However, this type of purification cleans as much air as your television. Most UV light cleaners are ozone free and will not damage lungs, but they also will not actually kill the pathogens. Air purifiers zip air through the filters and out the vents, creating air circulation in a room. Hospital UV lights are effective in killing particles by reducing or eliminating airflow.

Also, air purifier manufacturers do not usually explain what kind of UV technology they used, and some of these technologies produce high volumes of ozone. Ozone is not an effective or safe way to eliminate airborne pathogens. air purifier singapore dealsSince UV lights are not effective purification methods and could generate ozone, it is best to avoid air filters with this technology, or turn it off.best air purifier for nail salons Air purifiers are an excellent tool in the fight against indoor allergens and pathogens. consumers digest best air purifierHowever, you should pay close attention to the technology the air filter uses. Clean air is not worth damaged lungs. September 2010 Canadian Ratings Our tests reveal which ones deliver

This article appeared in September 2010 Consumer Reports Magazine. Viruses, airborne toxins, dust mites, pet dander in the air—it's enough to make you want to hold your breath or, if manufacturers have their way, buy an air purifier. Some of the 30 models we tested were quiet and effective; two did so little that we judged them Don't Buy: Performance Problem. Some air purifiers can remove or reduce smoke, dust, and pollen from your home. The Whirlpool AP51030K, $300, and Hunter 30547, $260, worked very well even at lower, quieter fan speeds. That's important because most people put portable purifiers in bedroomsOther models, such as the Airgle 750, $800, and FilterStream AirTamer A710, $280, cleaned very well only at the highest, noisiest speed. But no air purifier alone will relieve asthma and allergy symptoms, and if you don't have respiratory problems, you probably don't need one. We focused on portable and whole-house models that use filters because they don't produce ozone, a respiratory irritant that

can aggravate asthma and cause permanent lung damage. We also tested two widely available purifiers that rely on electrostatic(For more information on the various technologies used in purifiers, see Guide to purifier types and technologies.) And we even tested one that claims to transform plants—yes, plants—into effective air cleaners. Here's what else we found: Nonfilter products were lacking With no fan to aid airflow, the LightAir IonFlow 50F, $400, was about as effective at removing dust and smoke in our tests as having no purifier at all, though it didn't emit ozone. We judged the Light-Air a Don't Buy: Performance Problem. AIR12GU, $400, "electronically charges dust, allergens, and germs and pulls them out of the air like a magnet," its makerBut the Oreck was only slightly better than the LightAir at removing dust and smoke on its lowest speed and only fair on its highest speed—and it produced low levels of ozone. The most effective ones are usually professionally installed and cost hundreds.

One do-it-yourself filter, the Web Plus Adjustable Electrostatic 20x25x1, $17, is claimed to trap dust and pollen but was ineffective in our tests. Unlike the more effective do-it-yourself filters we tested, it was only marginally better than a standard furnace filter, which is meant only to protect equipment, not purify air. The Web Plus is also a Don't Buy: Performance Problem. Some claims by manufacturers have prompted government responses. The Federal Trade Commission last year ordered several companies to stop marketing purifiers as being effective against the H1N1 virus. The Environmental Protection Agency cautions that air cleaners outfitted with ultraviolet light are unlikely to kill bacteria and mold because they won't be in contact with UV light long enough to have any effect. And Florida's attorney general warned residents that using an ozone generator would make wiring problems associated with defective Chinese drywall worse, not better.