When it comes to air purification, experts suggest trying whole-house options, such as furnace filters, before making a big investment in a stand-alone air purifier. Filtrete filters get the most positive feedback from both owners and in professional reviews.
These filters come in a variety of sizes and filtration levels, from a 600 microparticle rating (MPR) up to 2,400 MPR. Filtrete filters vary in price depending on size and the level of filtration, from about $10 to $25 per filter. Owners say the Filtrete filters are highly effective, and many report a noticeable reduction in their allergy and asthma symptoms after using these filters with their home forced-air heating and air-conditioning systems.
All of The Filtrete filters draw positive feedback. We saw the most for the Filtrete Healthy Living 1550 Air Filter (Est. $30 each and up). It earns a Recommended label in one professional test and draws solid feedback from owners, including a 4.6-star rating following more than 300 user reviews at Amazon.com
The biggest benefit to using a furnace filter, besides being able to purify your entire home with a single purchase, is that they don't contribute any additional noise beyond what your furnace creates. Most furnaces recommend using filters anyway, but using a Filtrete Healthy Living 1550 is an additional step for removing allergens that can cause respiratory problems in asthma sufferers and worsen the symptoms of allergies.
The problem with ultraviolet (UV) air purifiers, or combination units that include UV light bulbs, is that the science isn't conclusive.
In one six-year study published in 2003 by the U.S. Centers for Disease Control and Prevention, UV lamps installed in the ceiling of a hospital room (not in an air cleaner) inactivated tuberculosis-like bacteria in the room. In a 2003 study published in the British medical journal The Lancet, germicidal UV lights installed in an office ventilation system significantly reduced workers' breathing problems and overall sickness.
However, most home versions are ineffective, according to both the EPA and the Federal Trade Commission (FTC). "Typical UVGI [ultraviolet germicidal irradiation] cleaners used in homes have limited effectiveness in killing bacteria and molds," the EPA says. "Effective destruction of some viruses and most mold and bacterial spores usually requires much higher UV exposures than a typical home unit provides."
The problem is primarily because air flows in and out of an air purifier, so it's not in contact with the UV light long enough for it to effectively kill any bacteria, and without a filter, these units won't actually remove small particles from the air. For now, it's not clear whether UV air purifiers are worth the extra expense over a good HEPA unit -- and none of our sources highly recommends them. In fact, we found no recommendations among our review sources for any air purifiers using ultraviolet technology.
While many turn to air cleaners and air purifiers as a first step in reducing indoor allergens and odors, the EPA and other experts instead suggest those as a last resort. The first steps, they say, should be to control sources of allergens and to adequately ventilate your living spaces. Some strategies -- such as removing a beloved pet -- might not be practical or desirable, but others are relatively simple and can be surprisingly effective. One, for example, is to use a dehumidifier to help reduce both mold spores and dust mites, which flourish as humidity levels go up. For more ideas, see the list of things to try at the Asthma and Allergy Foundation of America web site.