Our roundup of the best air purifiers has something to suit every budget. We’ve tested dozens of purifiers to bring you the best models to keep your air clean.
We spend a lot of time worrying about the quality of the air outside, but it’s inside that we should really be concerned about. From chemicals in cleaning products and hair sprays to dust and pollen, our home environments probably aren’t as clean as they could be. An air purifier is a handy way of keeping control, cleaning pollutants and making the air cleaner. In particular, if you (or a family member) has allergies or asthma, an air purifier can help a great deal.
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What can air purifiers do?
Air purifiers use a fan to pull in dirty air at one end, remove pollutants, and output clean air at the other end. The exact pollutants that can be cleaned depend on the technology used. All of the air purifiers that we’ve tested here use a HEPA filter, which will capture a minimum of 99.97% of airborne particles 0.3µm in size. Also known as particulate matter, these particles can penetrate your lungs causing respiratory problems, particularly in allergy sufferers.
Particulate matter sources include dust, with cleaning likely to disturb dust and throw it into the air, pet hair and dander, smoke and pollens. HEPA filters are no good where dust has settled, since the filters can remove only airborne particles. In other words, you still need to clean effectively. HEPA filters also have a lifespan, after which they’ll need to be replaced. The exact timing will depend on the air purifier and how dirty your air is, but expect to buy a new filter between three months and 12 months of operation.
Volatile Organic Compounds (VOCs) are harmful chemicals that are often found in cleaning products, paints, and some beauty products. VOCs are also found in some manufactured products, such as synthetic carpets and old furniture. Most air purifiers can’t touch these pollutants; those that can, can’t filter all VOCs.
Instead, you’re better off with an air monitor, such as the excellent Foobot, to monitor your home to see what’s giving off VOCs. Where possible, switch to less harmful products. Some models of air purifier also have an ionisation option. These use negative ions, which causes particles to stick to surfaces, such as wall or floor. Ionisation has been shown to reduce the risk of some viruses. Ionisation on its own isn’t particularly effective, so always combine with a proper air purifier.
What else should I look for?
All air purifiers use a fan of some description, so look for one that runs quietly enough for your intended use. We measure sound at maximum and minimum settings to help you choose. An automatic mode that ramps up the fan when the purifier detects dirty air is useful, as you can leave the purifier to do its job. You need to match the air purifier you buy to the size of room or space that you want to keep clean. Purifiers are rated by the square metre, so buy one that’s big enough.
Finally, you can look out for the Clean Air Delivery Rate (CADR), which tells you how effective the purifier is at different types of allergen, compared to introducing clean air. For example, an air purifier with a CADR score of 190 for dust particles, is as effective as adding 190 cubic feet of clean air per minute. In short, the higher the CADR rating for each type, the better. And, CADR scores are comparable across all products, helping you make the right choice.
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CADR has three main ratings to help you decide: smoke uses very small particle sizes of 0.09 to 1µm; dust has particle sizes of 0.5 to 3µm; and pollen uses particle sizes of 5 to 11µm. It’s best to choose your air purifier based on how effective it is at the pollutant you want to remove. Hayfever sufferers, for example, should choose an air purifier that’s efficient for pollen removal.
Finally, since air purifiers come in different sizes, the CADR rating should equal (or exceed) 2/3 of your room size in square feet. A 135-square foot room would need CADR ratings of 90 or above, for example. While CADR ratings are your best guide, we tested that each product was cleaning by using a spray of insecticide, which added VOCs and particulate matter to the room. We measured the drop of PM using our Footbot sensor, recording how long it took to return the air to normal levels.
Vax Pure Air 300 Air Purifier
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- Room size: 120m2
- CADR ratings: 428 (smoke), 392 (pollen), 278 (dust)
- 760 x 320 x 320mm
- Five speed settings
- Automatic mode
- three-to-six months’ filter life
It might look a little like a fancy bin with an ashtray for smokers on top, but the cylindrical Vax Pure Air 300 Air Purifier looks good in glossy white plastic and is easy enough to place out of the way. It has a HEPA filter – designed to last three to six months, depending on usage – and an ionisation option. The purifier’s front panel is dominated by simple-touch controls that let you power on the Air 300, control the fan speed, use the timer, and toggle the ioniser function. These options are replicated on the simple, slim-line remote control.
The big indicator light on the front changes colour to show you current air quality, moving from green, through amber to red. At minimum fan speed, I found the Vax Pure Air 300 ran at 35.9dB and a more intrusive 62.1dB at max. The night mode cuts the status lights and drops fan speed to a lower level, with sound falling to a quiet 33.4dB. Although it was still audible, you could easily sleep through its low-level noise. Power efficiency is excellent, with max power drawing a peak of 53.8W, and the minimum setting just 7.2W
Most people will find it easiest to run the Air 300 Air Purifier in automatic mode, with the device choosing the best fan speed to deal with current air conditions. I found that the fan never fully turned off, which is a little disappointing. Still, there’s a timer option – hourly increments of between one and eight hours – if you want the Air 300 to power down.
Regarding effectiveness, the Air 300 has high CADR ratings for smoke, pollen and dust. In our synthetic test, it cleared the particulate matter from of our insect spray in 1min 8secs. If you want a powerful all-rounder, this is the model to buy. Those who want something quieter should buy the Philips Air Purifier Anti-Allergen with NanoProtect Filter AC3256/30.
At the time of review, the Vax Pure Air 300 Air Purifier was available for £300.
Philips Air Purifier Anti-Allergen with NanoProtect Filter AC3256/30
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- Room size: 95m2
- CADR ratings: 234 (smoke), 253 (pollen), 226 (dust)
- 798 x 474 x 340mm
- Five speed settings
- Automatic mode
- 24 months’ filter life
The majority of air purifiers are rather drab looking, but Philips has gone all-out with its Air Purifier Anti-Allergen with NanoProtect Filter AC3256/30, and it looks great. Tall, yet relatively thin, this air purifier is easy to tuck out of the way. As you’d expect from Philips’ top-of-the-line air purifier, the AC3256/30 is packed full of features. For starters, it has a particulate matter (PM) sensor. Thanks to the LCD on top, you can accurately see the level of small particles currently in your home.
This model comes with two filters. There’s a NanoProtect filter that reduces odours and can filter some VOCs, and lasts for up to 12 months – replacements cost around £30. Then there’s the HEPA filter, which lasts for around 24 months – replacements cost around £40. Thankfully, the AC3256/30 notifies when both filters need replacing; if you don’t do the job within 14 days, the entire machine locks down to avoid damage.
All controls are accessed from the top, using the touch-sensitive panel. Unfortunately, there’s no remote control. Parents will be pleased to see that there’s a child lock, stopping little hands from activating the device. From the control panel, you can choose the fan speed, set the timer (in one-hour increments between one and 24 hours), and adjust the brightness of the controls.
Most people will find it easiest to operate the AC3256/30 in automatic mode, where the fan speed ramps up as the air quality deteriorates. There’s a standard auto mode and a more sensitive allergen mode. Usefully, the colour lamp at the front offers a visual indicator of air quality, moving from blue (good) through amber to red (poor). This lamp is dimmed when you dim the controls, so that you can use the AC3256/30 in a bedroom.
At the lowest setting, the AC3256/30 is silent, and I measured noise at 33.4dB – essentially this is just regular background noise. At full tilt, sound jumped to 56.7dB. Spraying insect spray saw PM levels drop back to normal in 1min 45secs. High CADR ratings in all categories show that this is a powerful air purifier, lagging slightly behind the Vax Pure Air 300.
If you want a very quiet air purifier, or a model that’s designed for pollen and allergies, then this is the model to buy. The Vax Pure Air 300 is slightly cheaper and a better all-rounder, but it doesn’t look quite as nice and it’s louder too.
At the time of review, the Philips Air Purifier Anti-Allergen with NanoProtect Filter AC3256/30 was available for £370.
HoMedics Brethe Air Purifier
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- Room size: 85m2
- CADR ratings: 123 (smoke), 149 (pollen), 136 (dust)
- 400 x 340 x 220mm
- Four speed settings
- 18 months’ filter life
With its array of four fans, the HoMedics Brethe Air Purifier looks like quite the beast. HoMedics claims that its nano coil filters are five times the equivalent of a HEPA filter, capable of killing some viruses too. Certainly, its CADR ratings prove that this is a capable air purifier.
As well as the nano coil filter, there’s an optional VOC filter in the box, which is easy enough to fit. A carbon filter reduces odours and there’s a pre-filter for larger allergens and pet dander. The nano filter is set to last for 18 months and can be replaced at a cost of around £40. A light on the unit warns you when the filter needs to be replaced, so there’s no guesswork involved.
A simple remote control duplicates the controls on the main unit. You can set the fan speed and timer (one, four, eight or 12 hours). There’s no automatic running mode on this device, so you’ll need to control it manually.
Running at full speed, the PM part of our insect spray was reduced to normal levels in just under two minutes, while the Brethe ran at a volume of 61.3dB. The Quiet fan mode drops sound to 42dB: that’s loud enough to hear but quiet enough to sleep through. Power usage is pretty good, with the Brethe running at 23.8W at maximum power and 5.1W at minimum.
The Vax Pure Air 300 is more powerful and the Philips AC3256/30 is quieter, but if you want a well-priced all-rounder then the HoMedics Brethe Air Purifier is a good choice.
At the time of review, the HoMedics Brethe Air Purifier was available for £150.
HoMedics Professional HEPA Air Purifier AR-20
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- Room size: 72m2
- CADR ratings: 117 (smoke), 123 (pollen), 126 (dust)
- 460 x 410 x 180mm
- Three speed settings
- Cleanable HEPA filter
The HoMedics Professional HEPA Air Purifier AR-20 has a slim yet wide case, which makes it relatively easy to position out of the way. It’s a mid-size air purifier, able to take on rooms up of to 72m2. It’s one of the cheaper HEPA filter purifiers out there. Neatly, the filter can simply be vacuumed to keep it clean, with the Professional HEPA Air Purifier warning you when it’s time to do this job via the LED indicator on the control panel. Replacements can be bought for around £20.
As you’d expect from a product at this price, its controls are rather simple. On top there are power, fan speed and timer controls; these are replicated on the slim-line remote control, too. There’s no automatic operation mode, nor an indicator to display the current air quality. However, you can run the unit on a timer so that it doesn’t over-run, selecting two-hour increments from two to 12 hours.
Running at maximum speed, the Professional HEPA Air Purifier managed to clean the PM part of our insect spray in just over two minutes, running at a fairly loud 62dB. Dropping fan speed to minimum, sound reduced to 42dB, which isn’t too bad and easy enough to sleep through. Power usage is a little high, and we measured the Professional HEPA Air Purifier as drawing 78.6W on maximum and 43.4W on minimum settings.
CADR ratings are mid-range across the board, showing that this is an effective purifier for general use. For a good-sized room, where you want a simple air purifier, the Professional HEPA Air Purifier is a well-priced option. For larger rooms or more powerful purifying, turn to the Philips AC3256/30 or Vax Pure Air 300 Air Purifier.
At the time of review, the HoMedics Professional HEPA Air Purifier AR-20 was available for £100.
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- Room size: 28m2
- CADR ratings: 80 (smoke), 89 (pollen), 78 (dust)
- 333 x 248 x 133mm
- Two speed settings
- 2000 hours’ filter life
Not all air purifiers are giant boxes, as the Dimplex DXAPV3N shows. This is a small box that’s designed to fit on a desk. It can clean an area up to 28m2, making it suitable for smaller rooms. It’s also one of the least expensive HEPA-filter purifiers available. To get the price down, the DXAPV3N is a rather simple product. It can’t display the current air quality; there’s no remote control; and there’s no sleep timer. There is a carbon filter built in, designed to neutralise odours, and it emits negative ions to help reduce the risk of some viruses.
The operation is simple, using the two-speed dial on the side. At the maximum setting, I measured noise at 49dB; switching to the low-power setting, sound dropped to 47.4dB, which is still fairly loud. It’s a shame that there isn’t a quieter night-time mode. Power efficiency is pretty good, with the DXAPV3N drawing 24.8W at maximum power, dropping to 15.5W at minimum.
At maximum setting, the particulate matter from our spray of insecticide took just under five minutes to return to normal levels. That’s comparatively slow, and confirms that this really is a product for a smaller room. The official CADR ratings bear this out, with low ratings for smoke, pollen and dust. Each HEPA filter should last for around 2,000 hours. There’s no warning to tell you when the filter needs replacing, so regular manual checks need to be taken.
If you have a small office or bedroom, the DXAPV3N could be a good choice. For larger rooms or much more effective purifying the Vax Pure Air 300 Air Purifier or HoMedics Brethe Air Purifier are better choices.
At the time of review, the Dimplex DXAPV3N was available for £55.