Air Purifier Buying Guide

Newer Homes Only

An air purifier can be a good choice especially if you live in a home that was built within the last 25 years. To meet energy use requirements, newer homes are more insulated and airtight than homes built before 1985. Fresh air won’t get in unless you open a window, which can be impractical. An air purifier will remove most airborne particles.

The best air purifiers can clear the air of particles larger than three microns. These air purifiers will eliminate dust, pollen, the visible particles in cigarette smoke, and animal dander. Air purifiers are not a solution to these problems, only a partial remedy. If you want a smoke or dander-free home, you’ll need to send the smokers and pets outside.

Health benefits of air purifiers

We’d all love to breathe cleaner air, and an air purifier can reduce the number of airborne irritants in the home. If you have seasonal or animal allergies, research suggests that an air purifier can make you more comfortable. For healthy people without allergies, an air purifier probably won’t give you any health benefits beyond the good feeling you have keeping an air purifier around.

Air purifier types

There are three basic methods that air purifiers use.

HEPA filters—These air purifiers draw air through a filter that traps airborne particles. The efficiency of a HEPA air purifier depends on the strength of its fan and the quality of its filters. The best HEPA air purifiers have powerful fans that can be too noisy for use in a bedroom.

Air ionizers—Air purifiers like the popular Sharper Image Ionic Breeze change the electric charge of air particles which causes them to collect on the purifier’s specialty surface. Ideally, the particles collect on metal plates inside the air purifier. In practice, the particles collect inside the air purifier but can also escpe to walls, floors, and furniture, which can be a burden if you don’t like vacuuming. These air purifiers generate small amounts of ozone, which can be a concern.

Ozone emitters—These air purifiers simply produce ozone. They don’t remove particles from the air, but they do neutralize odors from smoke and mildew. As with ionic air purifiers, the ozone can be a health concern. While there is no expert consensus on health effects, both the EPA and the American Lung Association recommend avoiding air purifiers that produce ozone, particularly if you have asthma or a respiratory condition. The EPA mandates that room ozone levels should be less than 50 parts per billion.

UV emitters—Ultraviolet light air purifiers do not remove airborne particles. These specialized air purifiers kill microbes and bacteria and offer limited real usefulness in a home setting.

Selecting an air purifier

When choosing an air purifier, first consider your needs. If pollen and pet dander control are important, look for a HEPA air purifier. If you need to reduce odors or cigarette smoke, an ionic or ozone-emitting air purifier will work.

Next, think about the size and layout of the room where you’ll be using the air purifier. For a small office or bedroom, a fanless air purifier may be sufficient. For a large, open living room, you may need more than one air purifier to notice a difference.

Finally, think about fan noise, ozone emission, and lifetime ownership costs. When comparing air purifiers, include the cost and frequency of filter replacement for three to five years to determine the lifetime cost of ownership.

Understanding performance

All air purifiers are rated for the amount of air they can clean. The Association of Home Appliance Manufacturers assigns a Clean Air Delivery Rate, or CADR, to al the air purifiers it tests. This number tells you how much clean air an air purifier can create per minute, based on a room with an eight-foot ceiling.

CADR is rated for dust, pollen, and smoke. On the specs, look for three CADR measurements; pollen, smoke and dust. The CADR indicates volume of filtered air delivered by an air cleaner. The higher the tobacco smoke, pollen and dust numbers, the faster the unit filters the air.

Since smoke is the toughest to clean, the easiest way to match an air purifier to a room is to multiply the CADR rating for smoke by 1.55. This will give you a rough idea of how much square footage an air purifier can clean efficiently (square footage = room length multiplied by width). Example: if you see a smoke rating CADR of 200, multiply 200x1.55=310. So a CADR of 200 will cover a room that’s 15x20, or 300 square feet. Still confused? Most manufacturers list square foot capacity if you don’t feel like double checking their math.

Air purifiers with fans may have a cubic feet per minute (CFM) rating instead of a CADR. Since an air purifier can only clean the air that it can circulate, this number gives you a general sense of its CADR, although the CADR performance of the air purifier will be a bit lower than its top CFM.

Still obsessed about CADR? Check out http://www.cadr.org/consumer/index.html for more info about how it works and pretty pictures of what pristine air looks like.

The Sharper Image lawsuit

Electrostatic air purifiers made by Oreck and The Sharper Image have outsold all other models despite the poor ratings they have received from Consumer Reports. These fanless air purifiers are quiet and have a low lifetime cost because they use metal collection plates that can be cleaned, eliminating the expense of filter replacement.

In 2003, following a string of poor reviews for its air purifiers, The Sharper Image sued Consumer Reports on the grounds that its testing results were wrong. The courts sided with Consumer Reports, and The Sharper Image has since sought out approval from private organizations such as The Asthma and Allergy Foundation of America.

When you’re comparing air purifiers, beware of these endorsements from advocacy groups. Look for air purifiers rated and tested by independent organizations, such as the Association of Home Appliance Manufacturers, and try to find an affordable air purifier that will meet your unique needs.

Need to know more?

• Air Cleaner or Purifier Care & Maintenance Tips
  http://housewares.about.com/od/aircleanerspurifiers/qt/aircleanercare.htm?terms=air+purifier
• 11 Critical Factors to Consider When Buying an Air Purifier
  http://www.inspiredliving.com/airpurifiers/air-purifier-buyingguide.htm
• Information on Air Purifiers and Cleaners
  http://www.airpurifiershopper.com/