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Why is Dyson challenging the industry standard CADR test?

Dyson CADR Testing
(Image credit: Dyson)

Choosing an air purifier can be a daunting task. First, discussions around indoor air quality are relatively new and industry research is limited. Second, how well can we judge the effectiveness of a machine that cleans an invisible substance. But ever since woman (we cannot be too sure it was a man) first lit fires in shelters, indoor air quality has been a health issue. Which is why we wanted to look into how Dyson, a company synonymous with air filtering solutions, tests the effectiveness of their purifiers.

In your search for the right purifier, you have most probably come across the term a clean air delivery rate (CADR) number, a metric developed back in the 1980s to measure the amount of clean air volume that a purifier can provide within a set amount of time. Although there are different test standards around the world for generating a CADR metric, they all follow a similar process and test within similar test chambers. The problem is that the CADR test chamber is small, between 28m3 and 30m3, has one sensor and depends on a ceiling fan to circulate the air around the chamber. How many modern homes still have a ceiling fan?

Unsatisfied with this approach, Dyson purifiers also undergo an additional test method called POLAR – or to give its full name the Point Loading and Auto Response test. It was developed by Dyson scientists and engineers in 2018 to understand their purifiers’ performance within a real home setting. By removing the fan and enlarging the size of the test chamber to 81m3 space, the POLAR method reflects how air purifiers are used in modern day life.

During the POLAR test, the device is positioned in the corner of the room, rather than the centre, reflecting a more likely position for us to set an air purifier in our homes. Nine sensors are placed around the chamber – two per corner at different heights and one in the centre – to assess the evenness of purification throughout the room. In a real home context, this would ensure that a person on one side of the room receives a similar air quality to a person on the other side of the room.

Another thing the POLAR test method challenges is the purifier’s ability to accurately process the input from its onboard sensors and how well the device can continually monitor the room air quality. If a purifier does not have strong sensors and algorithm, then how will it be able to automatically turn on and keep room pollution levels low?

You do not have to visit a Dyson Research, Design and Development space to see how their purifiers process real-time data. Real-time data is available on all Dyson purifiers or through Dyson Link APP to allow users to understand the performance of their machine in the real-world. This includes a measurement of particles, detection of VOCs and oxidizing gases, and temperature levels.

While modern homes have become better sealed from outdoor elements, this has meant that increasingly pollution is getting trapped indoors. But whether that be PM2.5 emitted when cooking, VOCs released from cleaning products or the continuous off-gassing of formaldehyde from our living room furniture, we cannot just eliminate our sources pollution. We just need to get better at filtering all that filth out.

More about the latest air purifying range from Dyson

Dyson’s new air purifying range, the Dyson Purifier Formaldehyde, senses pollution with new solid-state formaldehyde sensors. According to Dyson, this range also has a Selective Catalytic Oxidisation (SCO) filter that destroys formaldehyde at a molecular level. The catalytic filter has a unique coating, with the same structure as the Cryptomelane mineral. Its billions of atom-sized tunnels are the optimal size and shape to trap and destroy formaldehyde, breaking it down into tiny amounts of water and CO2. It then regenerates from oxygen in the air to keep destroying it continuously without ever requiring replacement.

This article was created in partnership with Dyson.