Dyson’s Pure Cool Air Purifier Has a Terrible Clean Air Rating | Review

Dyson Pure Cool air Purifier Tower CADR Review

Dyson’s Pure Cool Air Purifier looks impressive. However a review of its clean air rating (CADR) reveals it does a poor job of providing clean air – the TP05 Air Purifier’s CADR comes in at just 164m3/hr. In that case, the Dyson Pure Cool air purifier puts out as much clean air as a $20 DIY air purifier:

DIY air Purifier

Now, I’ve admired Dyson’s engineering-first approach to product design for a long time. 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 that Dyson hadn’t changed air purifiers, just air purifier marketing.

Dyson Unveils Old Air Purifier Technology, New Advertising

Maybe I shouldn’t have been surprised. After all, purifiers are just fans and filters. They’re so simple anyone can DIY their own.

Dyson Air Purifier Review


But when Dyson’s purifiers achieved terrible results in the industry standard test, Dyson started criticizing the test. That industry standard test is the “clean air delivery rate” (CADR). Here’s what the test looks like:

Sqair air purifier CADR test Dyson claimed not good

It’s true, the CADR test isn’t perfect and it has its downfalls. CADR tests are done in a lab, not real-world rooms.

Learn more: what is CADR and why it’s useful »

However, Dyson seemed to go so far in criticizing the CADR test, that and promoting their own, that they got a few things wrong about CADR. Let’s clear things up.

Three Facts Dyson Got Wrong About CADR

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 particles 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 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.

Smart Air Sqair air purifier CADR tests particle sizes range


Bottom Line:

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 purifier effectiveness:

  1. When air passes once through the filter, what percentage of particles does it filter out?
  2. In a given amount of time, what percentage decrease in particles in the room air did the purifier achieve?

Closeup HEPA filter material

The whole-room effectiveness 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.

Dyson testing air purifier filtration EN1822

Nerd Note: The EN1822 is what defines the HEPA standards like 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.

air purifier filter efficiency like slam dunk test

Bottom Line

CADR tests for whole-room effectiveness. 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).

Dyson air purifier formaldehyde and benzene CADR rating

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.

CADR Applied to Gaseous Pollutants EPA

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.

Dyson pure cool air purifier tower


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 will have more information on hand to make better informed decisions. Data rules!

To find the 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.

Dyson Pure Cool air Purifier CADR Rating Review

#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.

Dyson internal Pure Cool TP05 air purifier test


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 purifiers that are simply effective into an opaque industry. We provide no-nonsense, honest purifiers to people (like us) who just want to breathe safe air.

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