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  • Why CBC Marketplace needs to use modern air purifier testing

    Using the outdated ‘CADR’ test method to judge purifier performance will mislead people into choosing the wrong purifier. So what else should you be considering?

    Dyson purifier in house

    As with other household technologies, test methods govern the world of air purifiers. Giving people a way to judge the effectiveness of their machine is important, because never before has the air we breathe, and the consequences of indoor air pollution been so front of mind.

    The problem is that the test method being used by CBC Marketplace shows how quickly a machine can move airflow through a filter, but it does not measure performance in a real home without the aid of circulating fans and with much larger rooms. It also fails to consider filtration quality and whether the smallest, most harmful pollutants are actually being removed.

  • We do not stand for consumers being misled, either by outdated test methods or media coverage. You will never find Dyson making engineering advances simply to ensure a piece of technology passes a one-dimensional test metric. And here’s why.

  • The test – Clean Air Delivery Rate or CADR – is designed around an older generation of purifier – big white boxes – which were favoured in the 1980s when homes had ceiling fans and software engineering was rudimentary. Many manufacturers still favour this test as it promotes big energy consumptive motors in white boxes, allowing them to tinker with old designs rather than invent anything new. A bigger motor, means a bigger CADR, which means a better machine goes the marketing. It is however, false.


    In using the CADR test, CBC risks perpetuating the marketing myth but worse still it misleads people on the real-world performance of air purifiers. We think it’s time to set the record straight and help debunk the myths surrounding the testing of purifiers and the sole use of the Clean Air Delivery Rate (CADR) as a metric to judge superiority.


    Using CADR alone as a measure of performance is like buying a car based solely on which one drives the fastest.


    The reality is when buying a car you will also consider other things such as noise of the engine, durability and lifespan, safety, functionality and smoothness of ride in all conditions.


    The Clean Air Delivery Rate (CADR) is simply a speed metric. It’s like the speedometer of a car. It measures how fast a purifier can clean the air in a small, controlled chamber. It is calculated by measuring how much faster a purifier removes particles from the air compared to how quickly they would naturally drop and settle on surfaces.


    But knowing how fast a purifier cleans a small test chamber doesn’t help you choose the right purifier for your home. From a functional standpoint, a purifier needs to be able to filter out particles down to a microscopic level and it needs to project and circulate the clean air so it reaches every corner of the room, without relying on environmental factors, or ceiling fans.


    Beyond functional abilities, consumers also need to consider real world impacts of adding a purifier to their environment such as noise level, energy use, ease of use, etc. In addition, many consumers care about additional functionality such as connectivity and multifunctionality.  Others will factor design and aesthetic into their choice. An educated consumer should not pick a purifier solely on the speed metric.


     The CADR metric is outdated


    Some test methods used to achieve the CADR metric date back to the 1980s. Purification technology has advanced significantly since and the rooms these purifiers are placed in continue to grow.


    CADR does not consider what airborne pollution is being filtered or how effectively. It pays no testament to the advances in filtration technology and the ability to remove nasties such as formaldehyde from the air.


    It is crucial that test methods continue to evolve alongside these technological and home advancements.  Dyson regularly speaks with standards organizations across the globe to actively communicate our concerns with current test methodologies. In fact, the Chinese Household Electrical Appliances Research Institute (CHEARI) which standardizes test methods in Mainland China, the world’s biggest and most advanced purifier market, has already adopted similar test methodology to the Point Loading Auto Response (POLAR) test, Dyson’s in-house test methodology.  


    A test method which is unrealistic of modern day living


    While each chamber used to achieve the CADR score may be slightly different, there are flaws that run through each test.


    • Room Size – The size of the test chamber ranges between 28m3 and 30m3. This is unrepresentative of the average size of a room in a real, modern home. Especially now as open concept floor plans are increasingly popular.  A machine could achieve a high CADR score based on this small chamber, but in reality the score achieved doesn’t mean the purifier is able to clean a whole room in your home as the results suggest.
    • Artificial Circulation – Before the test begins, a ceiling fan is switched on to mix the pollutant in the room. During the test a wall fan is also switched on to circulate the air around the room during the test. Many homes do not have ceiling fans and those that do may not always have them turned on. It is our firm belief that the purifier itself must be responsible for circulating clean air around the room and you cannot rely on environmental factors.
    • Max Mode – All purifiers are tested on their highest setting. In real world use, owners would rarely keep their product on this setting continuously because it could potentially waste energy and can be quite noisy. The test does not account for things like auto mode where the product would sense and react to a pollutant until it was cleared from the air.


    To read more about CADR and Dyson’s preferred test methodology (POLAR) please visit

  • In Summary:  CADR is a one dimensional and outdated measurement of the rate a purifier cleans the air in a small, controlled chamber which is totally unrealistic of real homes. It does not consider critical functions that purifiers need to realistically clean a whole room.   Dyson will not design products simply to perform well in an outdated test when the result would be to sacrifice real world performance. Through pioneering test methodologies, such as POLAR, we ensure our purifiers are engineered to sense pollutants and react in real time, purify effectively and project clean air to the whole room.


    CADR is one performance metric, a speed metric only. Other things you may like to consider when purchasing a purifier include:

    • Noise - How loud is the purifier? 
    • Energy efficiency - How energy efficient is the purifier?  Will it cost a lot to run?
    • Auto mode - Does the purifier have the ability to sense pollution moments and increase purification accordingly?
    • Filtration - What pollution is the purifier actually capable of cleaning? Does it capture or destroy volatile gases such as formaldehyde?
    • Projection – Once the purifier has cleaned the air, is it able to project purified air to every corner of the room?
    • Does it have an LED screen that shows you real-time air quality data from the room, so you know it’s working?
    • Does the purifier have HEPA grade filtration?
    • Is the purifier fully HEPA sealed so not even hairline seams in the machine allow pollutants through?
    • Does the purifier have additional functionality? Can it heat the room in winter? Can it humidify? Can it cool in the summer?
    • Is the purifier connected so you can control the machine using a link app and access air quality data?

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