Air Chamber Test vs. CADR

4 ways in which the air chamber test gives a better appraisal of real-world effectiveness.

CADR (Clean Air Delivery Rate) was developed by the Association of Home Appliance Manufacturers (AHAM) in an attempt to institute a common standard by which to evaluate air purifiers. However, the CADR testing method is controversial for several reasons. In which case, Surround Air uses the straight-forward air chamber test to determine the effectiveness of its air purifier models.

Below is a point-by-point comparison between these two testing methods:


CADR was devised with conventional air filtration in mind, since this typifies the type of air purifier manufactured by those appliance manufacturers belonging to the AHAM lobbyist group, measuring air flow and the percentage of particles captured by the filter. As a result, it does not take into account the effect of other proven air purification technologies, such as air ionization, germicidal UV and photocatalytic oxidation.

Air chamber testing simply measures the percentage of various types of pollutants removed from the air, regardless of the air-cleaning technology used.

Types of Pollutants

CADR is completely irrelevant for some of the pollutants people are most interested in removing, such as micro-organisms, chemicals and odors. The CADR testing method measures only solid particles.

In addition to ultra-fine particles, Surround Air also tests for the ability to inhibit mold cultures and to remove hydrogen sulfide. Hydrogen sulfide is one of the very worst, and most difficult-to-remove pollutants known to man. An air purifier's ability to remove H2S is a good indication of its ability to remove strong odors and volatile organic chemicals (VOCs).

Real World Application

Air chamber testing is straight forward, measuring the air purifier's ability to remove the pollutants present in the chamber. CADR is theoretical, factoring air flow and absorbability of the filter material.

As a result, CADR favors air purifiers with the strongest fans and thickest filtration media. In other words, it is geared toward more expensive and loud air purifiers that consume high amounts of power and energy, with expensive replacement filters.

In reality, air purifier users value low-noise models that use modest amounts of energy, with low replacement costs. In which case, the trick is to produce an air purifier that is effective, yet meets the demands of customers who do not want an overly expensive and disruptive air purifier.

Air chamber testing helps determine if a quieter, energy efficient air purifier featuring non-filter technologies is effective, in order to create a capable, yet user-friendly product to meet the demands of the consumer.


Images from Air Chamber Test