Air Purifier Information

Whole-house air filters

In addition to portable air purifiers, there are a few solutions for whole-house air cleaning used in conjunction with a furnace/central-air system. The simplest and cheapest option is a special allergen filter. These slip into your forced-air system to replace your regular filter in the return duct. The 3M Filtrete Ultra Allergen Filter 1250 (*Est. $17) is the best-rated such furnace filter in reviews. Furnace filters should be replaced at least four times a year. ConsumerReports.org has good information about these types of filters, which are usually made of pleated material to trap dust. These filters cut down on airborne dust and pollen very effectively but aren't good with smoke in one leading test. We also found some good information and reviews on furnace filters at FurnaceFilterCare.com.

Electronic whole-house air cleaners are more expensive than filters and require professional installation (which will cost at least $200, according to a leading review source). These models also work in conjunction with forced-air ducts to deliver filtered air to every room. The Lennox Healthy Climate HC16 (*Est. $350) does a better job removing dust and smoke than disposable furnace filters -- even the top-rated Filtrete brand -- in one leading test. However, Ed Sherbenou at Air-Purifier-Power.com says whole-house air cleaners don't work as well as portable units. He says whole-house units leave pockets of air (such as in corners) inadequately circulated, and they deliver cleaned air through a house's ductwork, which is often coated in years of accumulated dust.

AHAM and clean air delivery rate (CADR)

A concern for some Air purifier manufacturers is the testing method used by ConsumerReports.org, a method developed and promoted by the Association of Home Appliance Manufacturers (AHAM). You might see the AHAM endorsement sticker on packaging and in advertisements. AHAM initially developed the clean air delivery rate (CADR) standard, a measure that represents the amount of clean air produced by the air purifier per minute. By themselves, these numbers (there are three reported -- one for dust, another for pollen and one for smoke) don't mean much. Since room sizes are seldom exactly the same and window placement, ventilation, etc. are invariably different from home to home, the CADR number can't tell you how well a unit may work in your particular room.

When CADR numbers of various air purifiers are compared, they become more useful. You should be able to compare different models of the same capacity to tell which units might be better than others. The higher the CADR number, the better the air cleaner. The problem when we tried to do this was two-fold. First of all, manufacturers rarely make home air cleaners of the exact same room specifications. Secondly, for brands that do offer comparably sized air cleaners, the CADR numbers show little variety. Most are within a few points of each other and sometimes they are identical.

Lastly, AHAM doesn't test all air purifiers. Manufacturers must pay a hefty fee to have their performance verified by AHAM (between $5,000 and $10,000, according to one manufacturer representative we interviewed). At this time, 33 manufacturers have done so. There are many more companies that make air cleaners, many of them smaller brands that cater to allergy/asthma niche markets. A representative from a small company in Wisconsin says they only employ 12 people and can't afford to spend that kind of money for "another sticker." Some manufacturers consider AHAM's methodology to be flawed and don't use AHAM certification for that reason. Another organization, the International Association of Air Cleaner Manufacturers, also has a voluntary certification program for ozone-free air purifiers.

The AHAM has since expanded its certification program to allow air-filter manufacturers to indicate whether their products comply with American National Standard and Underwriters Laboratories ozone emission standards.

Air-purifier alternatives

House plants may also help purify your indoor air. In the 1970s and 1980s, researchers at the National Aeronautics and Space Administration (NASA) found that house plants eliminated volatile organic compounds (VOCs) from tightly sealed living spaces. NASA used mostly common plants, including English ivy, spider plant, peace lily, snake plant, philodendron and weeping fig. The University of Minnesota says the NASA experiments "generated the recommendation that you use 15 to 18 good-sized houseplants in 6- to 8-inch diameter containers to improve air quality in an average 1,800-square-foot house." However, other experts say house plants might not help much. Dr. Richard Shaughnessy, director of the indoor air program at the University of Tulsa, tells The New York Times that wet plant soil can be a source of mold spore pollution. The U.S. Environmental Protection Agency states, "There is currently no evidence… that a reasonable number of houseplants remove significant quantities of pollutants in homes and offices. Indoor houseplants should not be over-watered because overly damp soil may promote the growth of microorganisms which can affect allergic individuals."

Daily dusting and vacuuming are excellent ways to remove allergens, but experts say the best way to control allergens is at the source, such as keeping pets out of sleeping areas and sending smokers outside. Many experts, including those at the Mayo Clinic, recommend using a vacuum with a high-efficiency particulate arresting (HEPA) filter to keep the vacuum from releasing fine dust back into the air. However, ConsumerReports.org says that while HEPA vacuums are very effective at reducing emissions, some non-HEPA models have performed just as well in tests and may cost less.

You should be careful as you search for information about air cleaners on the Internet. Many sources of information that appear to be independently sponsored have hidden agendas. Remember that manufacturer marketing claims are designed to sell products.

Our bottom line reflects what medical experts say about air purifiers: There's evidence they may work in conjunction with allergen-source control, ventilation and frequent HEPA vacuuming, but an air purifier is not a cure-all in itself. The expert consensus is there's no need to buy an ozone-producing device, since there are so many HEPA filters -- the gold standard in air filtration when used correctly -- available on the market.

Free ozone test kits

Ionizing or electrostatic air cleaners produce ozone as a byproduct. Ozone can damage lungs, worsen asthma, irritate the throat and cause other respiratory symptoms, according to the U.S. Environmental Protection Agency. If you have an air cleaner and want to find out if it's emitting ozone, the not-for-profit International Association of Air Cleaner Manufacturers offers a free ozone testing kit at its website, IAACM.org.

Air-cleaner research

To get past some of the hype regarding air cleaners, read the U.S. Environmental Protection Agency's fact sheet: "Residential Air Cleaning Devices: A Summary of Available Information."

The EPA also has a report on "Ozone Generators that are Sold as Air Cleaners."

Long-term exposure to even low levels of ozone can increase the risk of death from respiratory illness, according to a study published in March 2009 in the New England Journal of Medicine. The study followed nearly 450,000 people in 96 U.S. cities between 1977 and 2000.

AllergyBuyersClub.com offers a 12-point checklist for choosing an air cleaner.

Janet Wilson of the Los Angeles Times reports on the California Air Resources Board's ban on home ozone air purifiers, which becomes final on Oct. 18, 2010.

Reuters.com posts the press release of IQAir's protest against Consumer Reports' review process for air purifiers.

Manufacturer websites are also good sources of information and product specifications:

3M Filtrete

Alen

AllerAir

Austin Air

Biotech Research

Blueair

EcoQuest

Honeywell single-room portable air cleaners (made by Kaz)

Honeywell whole-house air cleaners and replacement filters

IQAir

Lennox

Oreck

Rabbit Air