CADR, What Does it Mean?

An Important Comparison Tool
To the consumer, CADR is an important tool for comparing the overall performance of different makes and models of air cleaners. CADR stands for Clean Air Delivery Rate, a measure of the total volume of air that a particular air purification system cleanses of a specific pollutant in one minute. When the particle size and filter efficiency of any two air cleaners are the same (as they often are), CADR is the key to choosing the more effective system.

To ensure accuracy and fairness, CADR testing is performed only by an independent industry organization, the Association of Home Appliance Manufacturers (AHAM). CADR test results are recognized as accurate and impartial by the U.S. Environmental Protection Agency and the American Lung Association.

CADR test results are expressed in cubic feet per minute (CFM), with a number rating for three "yardstick" pollutants: tobacco smoke, dust and pollen. The higher the CADR test numbers, the better the overall ability of the unit to clean your indoor air.

• The size of the particle removed
• What percentage of particles are removed
• The volume of air actually moving through the system

Understanding Air Volume
To understand what air volume means, visualize two murky swimming pools with identical filter efficiency but different pumps. In one pool, the pump sends one-fourth of the pool water through the filter every hour. In two hours, the pool is only half as murky as before. In four hours the pool is sparkling again. In the second pool, the pump sends only one-tenth of the water through the filter every hour. It will take 10 hours to clean the water in this pool.

Air volume is often described as air exchange (the number of times the total volume of air in the room is processed by the unit within a given period of time). Some manufacturers substitute air exchange rates for CADR results, but they are not equivalent. CADR numbers give a much more precise report of an air purifier's performance.

For example, in the swimming pool analogy, "water exchange" might describe the 4 and 10 hours needed to clean the pools. A "clean water delivery rate" would also tell you how much sun block, leaf particles and hair are removed from the pool in one minute.

CADR works the same way, rating not just how much air is cleaned nor just what percentages of particles are removed, but the overall performance of the filtration system when both factors are examined.

While some manufacturers do not submit their air purification systems for independent AHAM testing, Blueair believes that CADR results should be central to your decision making process. An air purification system is an important investment in your family's health and well-being. We urge you to compare CADR results for the systems you consider. For more information about CADR testing, go to http://www.cadr.org

The AHAM Seal
The AHAM (usually found on the back of an air cleaner's box) will list three CADR numbers-one for tobacco smoke, one for pollen and one for 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.

Follow the 2/3 Rule
You'll always want a unit with a tobacco smoke CADR at least 2/3 your room's area. For example, a 10' x 12' room -120 square feet-would require an air cleaner with a tobacco smoke CADR of at least 80. If your room size is smaller, the unit will simply clean the air more often or faster. If you have ceilings higher than 8', you'll want an air cleaner rated for a larger room.

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