Air Purifers vs Filters

Do you really need an air purifier?

Many experts, including those at Consumer Reports, say that most people really don't need an air purifier at all. Although home air cleaners can be effective against larger airborne particles such as pet dander, dust and smoke, all of those allergens can be better controlled at the source by removing elements in the home that produce dust and by not smoking indoors, as well as by regular vacuuming and dusting.

Since portable air cleaners can remove only airborne pollutants, they are not very effective against dust mites and their droppings (they're too heavy to be airborne for long), which are a significant allergen for many people. They also don't remove most viruses or gases like carbon monoxide and radon. That's because air filters are most effective on particles larger than three microns, such as molds, pollen, dust, plant spores, pet dander and the larger particles in cigarette smoke. Air-Purifiers-America.com measures down to 0.3 microns, which includes most pet allergens, smog and germs.

Most reviews agree that those with severe allergies, asthma and bronchitis -- who need to control indoor air quality as much as possible -- may benefit the most from air purifiers, but only when used in conjunction with other allergen-control strategies such as ventilation and daily HEPA vacuuming. These reviews say there's little evidence that air purifiers are effective alone. The Allergy and Asthma Network/Mothers of Asthmatics takes this stance: "Air filters don't replace the need for eliminating or reducing indoor allergens. Beware of any manufacturer making health claims."

The U.S. Environmental Protection Agency has an excellent online document titled, "Residential Air Cleaning Devices: A Summary of Available Information" (see our Useful Links section for the link to that article). The EPA doesn't take a position either for or against home air cleaners, but states, "Some air purifiers, under the right conditions, can effectively remove certain respirable-size particles" (for example, larger tobacco smoke particles). Both the EPA and American Lung Association recommend that air purifiers be used as a last resort after allergen source control and ventilation. According to Consumer Reports, "In short, only those with respiratory problems are likely to benefit from using an air cleaner."

Before you run out and buy a $500 air purifier, you might make a $17 investment and try a simple whole-house furnace filter. If you have forced-air heating or cooling, these filters simply replace your regular furnace filter. Filters such as the 3M Filtrete Ultra (*Est. $17) are effective at trapping particles like dust and pollen, but aren't very effective with smoke. Filters need to be replaced every three months. Be aware that some furnace filters can reduce air flow, especially as they become dirtier.

Although such filters can reduce airflow in your system, we think they are worth a try if your main problems are airborne dust, pet hair and dander. A $15 or $20 furnace filter, according to Consumer Reports, can be just as effective as room-sized air purifiers in removing those allergens at a much lower cost.