Excellent at neutralizing VOCs
Humidifier function as a bonus
Below average for removing particulates
Expensive in the market
The Dyson PH04 features the now-iconic—if, subjectively, odd-looking—Dyson design of a large, oblong loop atop a solid base. The top of the base easily disassembles to provide access to the filters inside.
Underneath the filter section is the water basin for the humidifier feature.
About the Dyson Purifier Humidify+Cool Formaldehyde PH04
Dimensions: 36.33” x 11.02” x 12.28” (H x W x D)
Weight: 18 pounds
Finishes: White and gold, nickel and gold
User manual: Dyson Purifier Humidify+Cool Formaldehyde PH04 manual
What we like
It performs above average when detecting and neutralizing VOCs
Where the Dyson PH04 really shines is when it comes to reducing volatile organic compounds (VOCs). These are gasses that are slowly released from many common household objects, such as a new mail-order mattress, and can be harmful if inhaled.
Where the Dyson PH04 differs from other air purifiers that aim to combat VOCs is by specializing in the eradication of formaldehyde (hence, its name), thanks to its catalytic filter that breaks the chemical down and neutralizes it instead of simply trapping it. Practical cases where you might encounter formaldehyde in your home include glues, different kinds of finishes or lacquers, and some composite wood products: It’s a common industrial chemical that off-gasses at room temperature.
The PH04 is also great at sniffing out formaldehyde and other VOCs, thanks to its air quality detection features. While this detection component is nothing new for Dyson, the feature is still relatively uncommon. Using this feature, the PH04 can monitor the air quality of your home in real time and can be set to automatically kick on when the quality drops below a certain level: Think of it as a “set it and forget it” mode.
When it comes to actually scrubbing VOCs out of the air, the PH04 does so at a rate almost twice as fast as the average air purifier, and is currently runner up to our top performer on this test, the excellent Aura Air smart purifier.
Its built-in humidifier could be helpful for those recovering from sickness
The Dyson PH04 is best understood as a jack of all trades: It isn’t just an air purifier, it’s also a humidifier. This means the device can be helpful not only when you’re trying to clear smoke out of a room, or cut down on pollen after having the windows open, but it can also combat dry winter air.
One use case that immediately springs to mind is helping to soothe someone’s sore throat as they recover from an illness, while the medical-grade H13 HEPA filter works to contain any airborne pathogens, making their space safer for anyone trying to help take care of them.
Its smart features make controlling the unit a snap
Like most Dyson products, the PH04 is controlled primarily through a companion app, which provides access to all of its settings and all the data it’s collecting about your home’s air quality.
The app is easy to install, intuitive to use, and provides some interesting information in its breakdown of air quality. You can also set up integration with Alexa, Siri, and Google Assistant.
Not a fan of apps? There’s also an included remote, though it doesn’t provide air quality data. This is one instance where we definitely prefer the app, though we’re happy the remote is also an option.
What we don’t like
Its particulate filtering abilities leave a lot to be desired
While the Dyson PH04 can definitely help filter out particulates, during out testing it did so at a rate that was about 24% less than the average air purifier, and over twice as slow as the top performer in this category that we tested, the Medify Air MA 50.
While the Dyson PH04 will still get the job done (eventually), it’s clearly not the primary competency of the purifier.
What owners are saying
The Dyson PH04 is a somewhat niche air purifier, so there isn’t a statistically-significant body of user reviews posted online. Those that are posted, however, seem to be positive, awarding the Dyson PH04 an average of 4.5 out of 5 across major retailers.
Those who are happy with their Dyson PH04 mainly focus on the build quality of the device, which we can definitely attest to: It’s a well-made machine. These consumers also find value in all three of its modes.
Those who are unhappy with the purifier mostly find it provides underwhelming functionality when you consider its premium price.
Dyson offers a 2-year warranty that covers parts and labor. Typically, appliance warranties are limited to a single year, so we’re happy Dyson goes above and beyond the standard here.
Should you buy the Dyson Purifier Humidify+Cool Formaldehyde PH04?
Maybe—It excels in several aspects, but those aspects form a niche use-case
The Dyson PH04 is a chimera. It tries to provide several distinct functions, excelling at some, disappointing at others, and generally giving the impression that it’s trying to do too much at once.
The PH04 has three main functions: filtering out VOCs, filtering out particulates, and humidifying the environment. While these three functions are related, the two that it excels at—clearing VOCs and humidification—have some of the least overlap.
As we stated above, the medical-grade H13 HEPA filter plus humidification seems to be a slam dunk for helping those recovering from a sickness, but the particulate filtration is also one of its weaker performances. We’re unsure what scenario would demand you need both the ability to break down formaldehyde and also increase the humidity in the room. Maybe if you just got a new mattress delivered during a particularly dry winter?
Where we’d recommend the PH04 is to consumers who have a specific need for an air purifier that’s a rock star with VOCs and who, coincidentally, can also get use out of its humidifier feature.
If you aren’t interested in the device’s humidifier functionality, but are still interested in the formaldehyde/VOC performance and air quality monitoring, what you’re looking for is actually Dyson’s TP09, which lacks the humidifier feature and is available as a significantly lower price.
Prices were accurate at the time this article was published but may change over time.
Meet the testers
Mark Brezinski is a senior writer with over ten years of experience reviewing consumer tech and home appliances.
Dave Ellerby is Reviewed's Chief Scientist, and has a Ph.D. from the University of Leeds and a B.Sc. from the University of Manchester.
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