Do Air Purifiers Help With Allergies?

Americans spend more than $350 million each year on air purifiers ("air cleaners"), with 4.6 million units sold in 2007 alone. Although testing by Consumer Reports has found that air purifiers can't remove all allergens and pollutants from the air in your house, they can provide some relief from allergy-related symptoms. Several factors such as filter type and professional rating can determine how well these purifiers work in your home and thus how well they help your allergies.

Considerations

• Do your research first, and check an air purifier's efficiency rating. The Association of Home Appliance Manufacturers certifies each model with a CADR rating which measures cleaning speed. Look for a CADR rating above 350 as best, and avoid anything below 100. Also, check the MERV (minimum efficiency reporting value) rating. The top performers in the Consumer Reports tests typically have a MERV score higher than 10.

  Another consideration is the noise level, since you might be less likely to use a purifier if it keeps you awake at night. Although the fans in purifier units can cause noise, units with fans tend to be more effective than those without. One way to moderate this is to buy a unit designed to clean an area larger than the room where it's going to be placed. Due to the larger-capacity filter, you'll be able to clean the smaller room on low or medium speeds, which will be quieter.

  Look at the label of the unit to see if it addresses your specific health concerns and is rated to remove substances such as cigarette smoke, mold spores, pollen and dust. You should also make sure the filter changing and cleaning isn't too difficult, so it will be easy to change the filters when needed. Another must-have feature is a pre-filter, which protects the main gas filter media or the HEPA filter inside the unit from being used up prematurely.

  Note that the placement of any portable air cleaner can affect its performance. Any unit should be placed so its intake is near any identifiable source of pollutants such as an air vent. Otherwise, the air purifier should be placed away from any obstructions that could block the intake and outlet. Portable air purifiers are more effective when all the doors and windows in a room are closed.

Types of Air Purifiers

• There are portable purifiers for individual rooms, which are the cheapest option, and also whole-house air cleaners (used with forced-air heating), which are more expensive and must be installed professionally. But otherwise, purifiers come in six basic filter types: HEPA filter air purifiers, ozone air purifiers, carbon air purifiers, ionic air purifiers, ultraviolet light air purifiers, and purifying hydroxyl radicals. The only type that is helpful at specifically removing allergens is the HEPA filter. Also, note that there has been quite a bit of controversy surrounding ozone and ionic purifiers. Dr. James L. Sublett, chief of pediatric allergy at the University of Louisville School of Medicine, says that "Air purifiers that are marketed this way are often machines that produce ozone. Ozone is an air pollutant and should be avoided by everyone, especially someone with allergies or asthma."