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Best air purifier 2021: Clear the air and ease your allergies with the top purifiers


Sick of sniffling, sneezing and feeling low in your home? Find relief from your allergies with our pick of the best air purifiers

The best air purifiers can help to ease the symptoms of asthma, hay fever and other allergies by cleaning the air in your home, removing pollutants and irritants such as pollen, dust, pet dander and smoke. With good-quality air purifiers available from £100 to well over £1,000, there are plenty of great choices for every budget.

But with machines ranging from downright useless to ultra-effective, it’s essential you do your homework before you choose which one to buy. To help out, we’ve tested a selection of machines to pick out the best air purifiers you can buy – that is, the ones that quickly and efficiently clear the air and are easy to both set up and use. Not sure what to look out for? Have a read of our buying guide below, where we’ve summed up the key factors you need to consider before parting with your hard-earned dosh.

Alternatively, feel free to skip ahead to one of the following sections:

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Best air purifier: At a glance

For small rooms

  • Best budget air purifier: Russell Hobbs RHAP1001B Clean Air Compact | Buy now
  • Best low-cost air purifier for features: HoMedics Totalclean Air Purifier AP25 | Buy now
  • A high-tech purifying desk fan: Dyson Pure Cool Me | Buy now
  • Best purifier and humidifier for smaller rooms: Sharp UA-HD40U-L | Buy now
  • A strong mid-range air purifier: Blueair Classic 405 | Buy now

For mid-sized rooms

  • A great purifier and humidifier for mid-sized rooms: Sharp UA-HD50U-L | Buy now
  • Brilliant for removing dust, pollen and smoke – and it doubles as a humidifier: Philips AC3829/60 | Buy now
  • Best purifying fan and humidifier: Dyson PH01 Pure Humidify + Cool | Buy now

For larger rooms

  • Best low-cost air purifier for bigger rooms: Vax Pure Air 300 | Buy now
  • Best quiet purifier for larger rooms: Hoover H-Purifier 500 | Buy now
  • Best air purifier under £500: Philips AC3259/60 | Buy now

How to choose the best air purifier for you

How much do I need to spend?

Air purifiers can cost as little as £100 or well over £1,000, but it’s not simply a case of the more you spend, the better the machine. Indeed, we've found low-cost machines with features that are usually only found in much more expensive machines. But that’s not to say that a pricy air purifier is inevitably overpriced, with the Blue Air Pro L providing a high-tech way of easing allergy symptoms for larger areas. Also remember it’s not just the initial financial outlay you need to think about, with operational costs ranging from a few pounds a year up to over £70 per annum.

How do air purifiers actually clean the air?

Air purifiers use different kinds of filters to do their job – usually, a large washable, reusable pre-filter to collect the large particles, plus a finer filter, which is usually a disposable high-efficiency particulate air (HEPA) filter. The length of time this lasts varies, but on average expect it to need replacing every six months (or fewer if you use the machine less). It's the HEPA filter that catches all the tiny airborne nasties, and these are capable of catching particles as small as 0.3 microns – which is more than three times smaller than a cigarette smoke particle.

READ NEXT: The best humidifiers

What is the Clean Air Delivery Rate (CADR)?

The CADR aims to provide an objective measure of the effectiveness of a portable air purifier at dealing with different types of allergen. A purifier with a score of 250 for dust particles is as effective as adding 250 cubic feet of clean air per minute. Buyers should focus on the results of the specific pollutant they're aiming to eradicate, whether that’s pollen, smoke or dust, and many manufacturers will supply CADR figures for the most common.

Generally speaking, the higher the CADR, the larger the room it can purify effectively. It’s also worth comparing manufacturer figures for the maximum size of room as these can vary enormously, sometimes when the CADR does not.

Can air purifiers help protect against viruses?

Understandably, there has been a lot of talk over the last year around whether HEPA air purifiers offer any protection against viruses, including the Coronavirus. The answer is pretty complex. Most viruses – and the droplets of mucus and saliva that might contain them – are perfectly capable of filtering particles in the 20 to 500 nanometre range in which you’d find most viruses, including Sars-Cov-2. What’s more, the US Centre for Disease Control has advised that used properly, air purifiers can help reduce airborne contaminants, including viruses, in a home or confined space.

However, there’s no way to ensure that a HEPA air purifier would catch the virus prior to you inhaling it, and there are a lot of variables in play, including the type of filter used, the size of the room and the airflow in it. There’s also still a lot of discussion about the extent to which many viruses are spread through the air or transmitted through contact with respiratory droplets. In short, an air purifier might help, but there’s not enough evidence to make the case compelling.

What other factors should I consider?

  • Filtration performance should be your priority. Your symptoms will only be eased to a noticeable extent with an air purifier that works quickly to clean the air.
  • Noise is another factor – you don’t want to replace one irritation (allergies) with another (the sound of a jet plane in your room). For many, the hum is something that doesn’t bother them, but some purifiers can get very noisy. It’s also worth remembering that, while some machines are quiet on their lowest setting (where they’re often at their least effective), they might be loud on the fastest (where they’re working at their best).
  • Speed settings. Most air purifiers have a choice of speeds so you can keep it lower for sleeping and turn it up when the pollen count is high. A night mode can also help if you want a quiet setting and dimmer lights while you sleep – although we found this doesn’t always work as well as you’d hope.
  • An air-quality sensor, which enables the machine to switch itself on when the air quality becomes poorer, can be useful. After all, you can’t see when the air quality dips, for example, as the result of a high pollen count.
  • A few high-end units double as humidifiers, managing the moisture in the air to prevent dry air causing irritation to the nose, throat, lips and skin.
  • What about a carry handle? These are handy if you need to move it from room to room. Wheels, a compact design and a low weight won’t go amiss here either.
  • Easy-to-use controls are always a plus, with a good remote control a must-have when you’re using a purifier in a larger room. Some purifiers are even packing in Wi-Fi connectivity and apps, so you can set the purifier going before you get home from the office or control it from your phone.
  • Filter replacement indicators aren’t crucial and not all air purifiers have them, but this is a helpful feature as a clogged air cleaner won’t work properly.
  • Should you consider getting a timer? If you want your machine to come on a few hours before you’ll be using the room, or if you want to be able to turn it off automatically, this is a good option.

The best air purifiers for small rooms

1. Russell Hobbs RHAP1001B Clean Air Compact: The best budget air purifier

Price: £74.99 | Buy now from Robert Dyas

This pint-sized purifier doesn’t pack in many features, but it’s effective where it counts. It comes in black or grey and stands just 40cm high – roughly the size of a small pedal bin – with the intake at the bottom and a fan blasting air out at an angle at the top. With just three speed settings, three timer settings and a sleep mode, the controls are fairly basic, and the only indicator is an LED ring that fades from red through amber to green as the filters do their work.

It’s really designed for small spaces of around 10m2, but we found its performance better than the 80m³/h CADR might imply. Spraying antiperspirant into a small room with the purifier at maximum speed, the Clean Air Compact brought PM2.5 particulates down to safe levels within three minutes and six seconds. At that speed it’s fairly noisy, with sound levels reaching around 48dBA, but in general use the low setting will be fine, and this takes the noise levels down to 36.2dBA, where the sound is noticeable but hardly aggravating. Spending more will get you something quieter with more power, but this is a decent little purifier for a small lounge, home office or bedroom if you’re working to a similarly sized budget.

Key specs – CADR: 80; Max room size: 10m²; Power settings: 3; Dimensions (HWD): 40.3 x 19.5 x 19.5 cm; Weight: 2.3kg; Filter replacement indicator: Yes; Warranty: 2 years

2. HoMedics Totalclean Air Purifier AP25: The best low-cost air purifier for features

Price: £150 | Buy now from Argos

Hay fever sufferers and asthmatics, rejoice. This clears pollutants – especially cat and dog allergens, house dust mites and pollen – from the air at the kind of speed you’d expect from much more expensive machines. You don’t get all the bells and whistles you would with pricier machines (although you do get some, such as night mode, a timer and a filter indicator) and it’s quite loud on the fastest of the three speeds. But it’s endorsed by Allergy UK, looks smart, doesn’t take up too much room and is easy to move from room to room.

Key specs – CADR: Not stated; Max room size: 72m²; Power settings: 3; Dimensions (HWD): 54 x 53 x 29 cm; Weight: 5.33kg; Filter replacement indicator: Yes; Warranty: 2 years

3. Dyson Pure Cool Me: A high-tech purifying desk fan

Price: £300 | Buy now from Argos

Need a personal purifier for your bedroom or office? The Dyson Pure Cool Me could be the answer. Using technology borrowed from the Harrier Jump Jet, it sucks air in through the base and forces it out, purified, through two small openings and across the smooth domed surface. There they combine into a powerful single jet of air, ready to cool you down while in bed or at your desk.

It’s surprisingly effective for such a compact unit, dishing out plenty of air. At power levels one to three it’s practically silent, and noise levels aren’t even bothersome at the highest of its ten speeds. Meanwhile, the HEPA and active carbon filters do an impressive job of filtering out particulates down to 0.1um in size. Obviously, it won’t deal with larger rooms, but you’ll struggle to find anything better for personal cooling and air purification.

Read the full Dyson Pure Cool Me review

Key specs – CADR: Not stated: Max room size: Not stated; Power settings: 10; Dimensions (HWD): 40.1 x 24.7 x 25.4cm; Weight: 2.7kg; Filter replacement indicator: Yes; Warranty: 2 years

Buy now from Argos

4. Sharp UA-HD40U-L: The best purifier and humidifier for smaller rooms

Price: £285 | Buy now from Amazon

This compact unit packs in three ways to improve your air quality. It uses a triple air-filtration system to remove microscopic irritants and pollutants – not to mention odours – and can also humidify your air, adding tiny droplets of moisture from the 2.5l water tank to maintain a constant level. Finally, it features what Sharp calls “Plasmacluster ion technology” to emit positive and negative ions, which, Sharp claims, can eliminate bacteria and viruses, odours and static electricity.

We’re not sure how well that works in practice, but the UA-HD40U-L is impressively efficient at filtering out impurities and very quiet at its automatic and low-power settings. A strip on the top turns from red to orange to green to indicate the current air quality, and there’s a humidity readout so you can monitor humidity levels, although both this and the ‘ion shower’ feature can be turned off if you just want air purification. Well designed and easy to use, this is a great air purifier for smaller rooms.

Key specs – CADR: 216m³/h; Max room size: 26m²; Power settings: 6; Dimensions: 39.9 x 23 x 61.5cm; Filter replacement indicator: Yes; Warranty: 1 year

5. Blueair Classic 405: A strong mid-range air purifier

Price: £499 | Buy now from John Lewis

At almost £500, this purifier doesn’t come cheap. Nonetheless, Blueair has quite a reputation in the world of air purifiers and this model stands out for three reasons. First, both the machine and its associated app are easy to set up and use – seriously, it’s a doddle. Second, it does an incredible job of eradicating dust, smoke and pollen; while the spec says it’s good for rooms of up to 40m², its CADR figures show it can cope with medium-sized rooms. Third, it’s one of the quietest models we tested when on its lowest setting.

But there are downsides. It doesn’t look as smart or inconspicuous as some of the other machines and doesn’t have as many features, either. It’s quite noisy when turned to full whack and it’s not the easiest to move around. The filter changing process takes a bit of getting used to, although it's very good at letting you know when this needs to be done, which is roughly twice a year. If you can live with those things and want a machine that does its main task very well, this model gets a big thumbs up.

Key specs – CADR: 467m³/h smoke, 510m³/h dust, 510m³/h pollen: Max room size: 40m²; Power settings: 3; Dimensions (HWD): 23 x 20 x 11cm; Weight: 15kg; Filter replacement indicator: Yes; Warranty: 5 years

Buy now from John Lewis

The best air purifiers for mid-sized rooms

1. Sharp UA-HD50U-L: A great purifier and humidifier for mid-sized rooms

Price: £302 | Buy now from Amazon

The bigger brother of the UA-HD40U-L, the UA-HD50U-L combines the same impressive feature set with a bigger airflow to cover rooms of up to 38m², giving you enough purifying power to cover larger living rooms or open-plan spaces. It’s still quiet, too, putting out little more than a whisper at its lowest settings or when set to its advanced auto mode. In fact, the loudest noise it makes is when the rear vent opens just after you turn it on.

Otherwise, this has the same advantages as the smaller version: effective three-stage filtering, a built-in humidifying function and Sharp’s Plasmacluster ion technology, which – while it sounds like a weapon from a Halo game – works to kill odours, bacteria and mould. While the Vax PureAir 300 gives you even more airflow and covers larger rooms for less, the Sharp hits a sweet spot for price, performance and features, making it a great mid-range purifier for mid-sized rooms.

Key specs – CADR: 306m³/h; Max room size: 38m²; Power settings: 6; Dimensions: 39.9 x 23 x 61.5cm; Filter replacement indicator: Yes; Warranty: 1 year

2. Philips AC3829/60: Brilliant for removing dust, pollen and smoke – and it doubles as a humidifier

Price: £550 | Buy now from John Lewis

The Philips AC3829/60 easily justifies its steep price tag, thanks both to its excellence at purifying the air in your home and its abundance of bells and whistles. In terms of the main job in hand, it’s easy to set up and use and, crucially, it removes dust, pollen and smoke at a rate of knots. The purifier is also energy-efficient and quiet on the low speed, and although it’s louder on the highest of its four fan speeds, it has a night mode to quieten it down when you’re trying to get some shut-eye.

The AC3829/60 can be controlled using a smartphone app where you can set it to “general,” “allergen on” or “sleep mode”; you can also find real-time pollution data both inside and outside, and get weekly forecasts, among other things. There’s a timer and an automatic mode, and this model even acts as a humidifier

All in all, it’s hard to fault, but be warned that it’s big – even if it does have wheels. Our one complaint would be that replacing filters could be easier. If you’re not fussed about dehumidification, you can save a little cash by going for the similar – and cheaper – AC2889/60.

Key specs – CADR: 310m³/h; Max room size: 95m²; Power settings: 8; Dimensions (HWD): 80 x 49 x 39cm; Weight: 13.6kg; Filter replacement indicator: Yes; Warranty: 2 years

Buy now from John Lewis

3. Dyson PH01 Pure Humidify + Cool: The best purifying fan and humidifier

Price: £599 | Buy now from Dyson

As the name suggests, the Dyson Pure Humidify and Cool works as a fan, an air purifier and a humidifier. Fill the base of the fan with water and it’ll not only keep you cool, but filter and add moisture to the air at the same time. While too much humidity isn’t a good thing, too little can lead to snoring problems and respiratory issues, especially in hot, dry climates or the winter.

Like the Hot+Cool and the Pure Cool Me, the fan is able to use its activated carbon filter to remove gases and odours, while a HEPA filter extracts fine particles as small as 0.1 microns from the air.

The Humidfy + Cool comes with a remote control and can be controlled via your smartphone just like the Hot+Cool. It's an effective purifier and quite with it plus the humidifying aspect adds an extra element, keeping the air cooler than a normal fan. It is rather expensive, though.

Key specs – CADR: Not stated; Max room size: Not stated; Power settings: 10; Dimensions (HWD): 92 x 31.2 x 31.2cm; Weight: 8.92kg; Filter replacement indicator: Yes; Warranty: 2 years

Buy now from Dyson

4. ProScenic A9: High-tech features at a low-end price

Price: £169 | Buy now from Amazon

For a low-cost, compact air purifier, the ProScenic A9 packs in a lot of features, and it’s also capable of handling spaces of up to 90m2 in size. Its four stage filter is designed to absorb particles as small as 0.3 microns, and it includes an infrared sensor to display air quality and adjust the power level in response to any changes. This proved thoroughly effective in tests, ramping up the fan speed to deal with smoke from an open woodburner – while also ramping up the noise.

In normal operations, though, fan noise won’t be a problem. While the racket is pretty awful at the highest speed, it’s barely noticeable at the lowest setting and the A9 has a sleep mode that drops it down even further and turns off the display and any LED indicators.

And, if you don’t fancy using the buttons on the top of the unit, you can also set timers and change the settings over Bluetooth or Wi-Fi using ProScenic’s smartphone app (though why this needs access to your location and your phone’s cameras and photo library is a bigger question that will put some users off). Still, with or without the app, this is a great value purifier that makes some bigger brand models look cumbersome and dated.

Key specs – CADR: 460m3; Max room size: 90m2; Power settings: 4; Dimensions (HWD): 52 x 26 x 26cm; Weight: 5.94kg; Filter replacement indicator: Yes; Warranty: 1 year

The best air purifiers for larger rooms

1. Vax Pure Air 300: The best low-cost air purifier for bigger rooms

Price: £120 | Buy now from Amazon

This tall cylindrical air purifier offers remarkable value for money when it comes to removing pollutants from the air and it’s particularly easy to set up and get going. Like the Philips machine, it has clever air monitoring technology so that you can set it to automatically work harder when pollution rises in your home, plus a timer and sleep mode. Unlike the Philips machine, you also get a handy remote control. It’s quite loud, but if you don’t mind that, it’s hard to think of a machine that gives you more bang for your buck – and to top it all, it gets the Allergy UK Seal of Approval.

Key specs – CADR: 428m³/h smoke, 399m³/h pollen, 391m³/h dust: Max room size: 120m²; Power settings: 5; Dimensions (WDH): 32 x 32 x 76cm; Filter replacement indicator: Yes; Warranty: 2 years

2. Hoover H-Purifier 500: The best quiet purifier for larger rooms

Price: £279 | Buy now from Amazon

The mid-range model of Hoover’s new purifier range, the H-Purifier 500 comes packed with features and thoughtful design touches, including the retracting power cord, digital display and an LED ring that changes colour for an at-a-glance update on your air quality. It’s easy to use, too. Just set it in its Auto mode and it’ll run, continuously adjusting the fan speed, until the air quality stays in the safe green zone for over 30 minutes, at which point the fan will turn off. And if it gets worse again? No problem. It’ll kick straight back into action automatically.

This one has sensors for PM10 and PM2.5 pollutants along with VOC gases, and can also track temperature and humidity through the display. What’s more, link it to the hOn app over Wi-Fi, and the H-Purifier 500 will respond to other changes, including high pollen levels, soaring temperatures or pollution.

What we really like about this purifier, however, is that it’s both effective and pretty quiet about it. At full tilt it’s as noisy as most rival air purifiers, but in its sleep mode you’d struggle to hear it above ambient sound levels – we measured the output at just 31dBA. In our deodorant spray test, the H-Purifier 500 got the PM2.5 concentration down to safe levels within two minutes and eight seconds, and Hoover’s three-filter purification system has been approved by the British Allergy Foundation. We’re not 100% sure about the option to add essential oils to the airflow, but the options include an H-Biotics bottle that adds probiotic ‘good’ bacteria to the atmosphere. All in all, it’s a superior purifier that’s perfect for mid-sized and larger rooms, with a price tag that won’t leave you gasping.

Key specs – CADR: 330; Max room size: 110m²; Power settings: 3; Dimensions (HWD): 57.5 x 28 x 32 cm; Weight: 6.9kg; Filter replacement indicator: Yes; Warranty: 2 years

3. Philips AC3259/60: The best air purifier under £500

Price: £319 | Buy now from Amazon

While it launched at nearly £500, you can now find this Philips purifier for around £350 to £380, which makes it even better value. It gives you all you need to treat the air in larger rooms, covering spaces of up to 95m², and makes doing so an absolute no-brainer, with three automatic purification settings protecting against pollutants and allergens or keeping things quiet while you sleep. The allergen mode keeps the purifier on constant alert for risks, and you can monitor air quality at any point either using the display on the top or the connected smartphone app. You can also use the latter to control the AC3259/60 from anywhere or use voice controls courtesy of an Amazon Alexa skill.

It’s an effective unit, removing pollen, dust and smoke from the air at a rate that cheaper machines can’t compete with, and though the higher speeds make a fair old racket, the lower speeds are practically silent, with one of the quietest night modes around.

Key specs – CADR: 393m³/h; Max room size: 95m²; Power settings: 5; Dimensions (WDH): 25.1 x 36.6 x 69.8cm; Weight: 9.8kg; Filter replacement indicator: Yes; Warranty: 2 years

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