While Dyson’s Pure Cool air purifier looks impressive, a closer examination of its Clean Air Delivery Rate (CADR) exposes a rather bad performance. The Dyson TP05 Pure Cool passed a mere 164m³/hr in CADR. That means the Dyson Pure Cool air purifier out as much clean air as a $20 DIY air purifier. Read on to learn more.
Dyson Pure Cool Air Purifier Review
When Dyson launched their Dyson Pure Cool Air Purifier, I was excited to see what new tech or super-efficient design they would bring to the show. But what I found was a letdown. Dyson hadn’t changed the air purifiers. They’d just changed their marketing around air purifiers.
Maybe I shouldn’t have been surprised. After all, purifiers are just fans and filters. They’re so simple; anyone can make their own.
However, when Dyson’s purifiers achieved terrible results in the industry standard test, Dyson started criticizing the test. The “clean air delivery rate” (CADR) is the industry standard test. Here’s what the test looks like:
It’s true, that the CADR test isn’t perfect and it has its downfalls (CADR tests are done in a lab, not real-world rooms). However, Dyson seemed to go quite far in criticizing the CADR test. Due to the poor results of Dyson’s Pure Cool Air Purifier in the industry standard CADR test, Dyson markets their own tests which make the purifiers seem to perform better. Dyson got a few things wrong about CADR. Let’s clear things up.
Three Facts Dyson Got Wrong About CADR
Dyson makes claims to defend the Pure Cool air purifier and their other product’s low CADR rating. But many of their claims trying to discredit the air purifier industry standard are false.
Dyson Claim #1: CADR doesn’t focus on different particle sizes.
Dyson’s website claims that CADR doesn’t “focus on how well a purifier captures different particle sizes.” That’s flat wrong. There are essentially two standards for CADR tests. The AHAM (US) test and the GB-18801 (China) standard. The US standard tests for particles in three ranges, which they call “dust,” “pollen,” and “smoke.”
| Particle Name | Particle Size Range |
|---|---|
| Smoke (Tobacco) | 0.09 – 1.0 microns |
| Dust | 0.5 – 3.0 microns |
| Pollen | 0.5 – 11 microns |
The Chinese GB-18801 standard also tests and reports filter efficiency for particles ranging from 0.30 – 10 microns. That covers from the smallest, hardest-to-capture 0.3 micron particles, all the way to large dust and pollen particles. Here are the CADR test results for Smart Air’s Sqair air purifier.
In short, CADR tests do report efficiency for different particle ranges.
Dyson Claim #2: CADR doesn’t measure filtration efficiency
This one’s right but misses the point. There are two main ways to describe an air purifier’s effectiveness:
- When air passes once through the filter, what percentage of particles does it filter out?
- In a given amount of time, what percentage decrease in particles in the room air did the purifier achieve?
The whole-room effectiveness of Dyson’s Pure Cool air purifier is really what most users care about, and that’s what the CADR test measures. For single-pass filtration, there’s a separate official test and rating system for that, the EN1822 test. Elsewhere on their website, Dyson mentions that test, so they’re aware of it.
Nerd Note: The EN1822 is what defines the HEPA standards like the H13 we often see. If we want to know about single-pass filter efficiency, then we should look at the HEPA filter’s rating (e.g. H13/H14, etc.).
So this claim is like criticizing a basketball game for not measuring dunking performance. If you want to focus on dunks, there are dunk contests that do that. It’s not the main purpose of basketball games.
CADR tests a purifier’s ability to purify a whole room. For HEPA filter efficiency, then we should use the EN1822 HEPA rating system instead.
Dyson Claim #3: CADR only tests for particles
This is wrong. In fact, Dyson even contradicts themselves on this one. On their English website, they say CADR tests for particulate. But on Dyson’s Chinese Tmall product page, they provide CADR results for benzene and formaldehyde (gases).
The GB-18801 CADR test covers testing VOC gases such as benzene and formaldehyde too.
It’s possible that Dyson is only referring to the US (AHAM) test here. True, the AHAM test doesn’t specifically state that it can test for gases, although the EPA explains that it can.
Summary on Dyson's Air Purifier & CADR Claims
CADR tests have their downsides, primarily that they don’t represent real-world rooms. It’s great to see Dyson promoting real-world tests for air purifiers, just like Smart Air. However, CADR tests still have their use in helping air breathers make informed choices when buying air purifiers. CADR ratings should not be thrown out just because it performs poorly, such as Dyson’s Pure Cool Air Purifier
If Dyson is reading this, what can they do?
#1 – Be Open About the Pure Cool air purifier’s CADR Rating and Internal Test Results.
It’s really difficult to find information on the CADR on the Dyson website. If Dyson provided this – along with results from their own internal tests – consumers would have more information on hand to make better-informed decisions. Data rules!
To find Pure Cool’s CADR, we had to scour Dyson’s Chinese shop for details. In China, CADR results are required by law. We found the TP05’s particulate CADR of 164m3/hr, and a formaldehyde CADR of 56m3/hr at the very bottom of their TMall page.
#2 – Publish the details of the Dyson internal ‘TM-003711’ test method.
Dyson Engineer David Hill said, “We believe all air purifiers should be tested this way [using Dyson’s method]”. If Dyson’s test really is better than CADR, then openly publishing the testing method will benefit all air-breathers around the world.
Update: Dyson contacted us to say that they have published the testing method (although only in Chinese). It’s worth noting, however, that this test method is for testing an air purifier’s ‘smart mode’. More specifically, it tests the accuracy of an air purifier’s built-in air quality monitor, and its ability to react to nearby pollutants. Although this is a much-needed test, this is different from a filtration effectiveness test. That means it shouldn’t replace CADR tests, but be used as an additional test for purifiers that contain air quality monitors.
UPDATE: 20th February, 2021
Dyson got in touch with us to clarify their position on CADR:
We simply don’t engineer purifiers to perform well at this test [CADR] as we don’t believe it to be useful for consumers, but rather we choose to develop machines that perform well in real homes, in a test that more accurately demonstrates real-world performance.
About Smart Air
The air purifier industry is opaque. It’s profit-driven, not health-driven. Big companies charge hundreds or thousands of dollars for technology that was invented over 70 years ago. We created Smart Air to bring open data and simple, effective air purifiers to the opaque industry. We provide no-nonsense, honest purifiers to people (like us) who just want to breathe safe air.
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