Air Purifers vs Filters

Do you really need an air purifier?

Many experts, including those at ConsumerReports.org, say most people don't need an air purifier. 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. Most air cleaners also don't remove most viruses or gases like carbon monoxide and radon. That's because even high-efficiency particulate arresting (HEPA) 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. However, some pricier HEPA air purifiers, including the top-rated IQAir HealthPro Plus (*Est. $900) and Austin Air HealthMate (*Est. $450), add carbon filters that they say can remove much smaller particles.

Most reviews agree that people with severe allergies, asthma and bronchitis -- who need to control indoor air quality as much as possible -- may benefit 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 (EPA) 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, "The use of air cleaners may help reduce levels of smaller airborne allergens or particles, but should not be expected to effectively reduce health symptoms." 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 ConsumerReports.org, "Americans spend more than $350 million each year on room and whole-house air purifiers -- also known as air cleaners -- mostly in the hope that they'll ease the symptoms of asthma and allergies. But there's little medical evidence that any air cleaner alone can do that effectively."

Before you buy a $500 air purifier, you might make a $17 investment to 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 Allergen Filter 1250 (*Est. $17) are effective at trapping particles like dust and pollen in one leading test, 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.