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How to buy the best air purifier

By Christina Woodger

Expert tips on how to buy the best air purifier that will clean the air in your home quickly and effectively without making too much noise

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A good-quality air purifier will do a great job of cleaning the air in your home. But there are also plenty of air purifiers that are pitiful at extracting polluting particles.

Read on to find out if an air purifier is right for you, the types available, how much you should expect to pay and some of the best models on the market.

If you already know the type of air purifier you want, head straight to our best air purifier reviews

In this article: 

Video: how to buy the best air purifier

Watch this video to help you buy the best air purifier for you.

Do I need an air purifier? 

If you suffer from allergies an air purifier would be a good investment, provided you buy the right model.

Our tests show that using an air purifier in your home will reduce the number of pollutants in the air, such as dust, pollen and smoke. All of the models we’ve tested removed at least some particles from the air, but the difference between the best and worst is enormous.

In our lab tests, we found that the best air purifier for removing dust was more than 26 times more effective than the worst. In your home, this means it would take much, much longer to clean the air, which is no good for you if you’re allergic to household dust.

Types of air purifiers 

Desk air purifiers

As the name suggests, desk air purifiers are compact enough to sit on a desk or a shelf in your home. They’re not as powerful as bigger machines, but they tend to cost less to run and can be effective in small rooms. 

But read our air purifier reviews before you buy, as one desk air purifier we tested didn’t pack much of a punch at all. It was 26 times less effective at extracting dust from the air than the best we tested.

Tower air purifiers

Tower air purifiers are tall and often cylindrical. They can be powerful enough to work in large open-plan spaces in the home. In terms of dimensions, some can be as large as a tall, cylindrical kitchen bin. Others are roughly the same height but much slimmer.

Large portable air purifiers

This type of air purifier is roughly the size of a hand luggage flight case, and the best are able to effectively clean the air in a large living space. 

Some can be highly powerful in terms of wattage, which pushes up running costs. But most are mid-range power-wise.

Oscillating air purifiers

Oscillating air purifiers can be fan-based or desk-based machines and can be set to rotate as they clean the air.

Air purifiers that double as fans

The Dyson Pure Cool Link TP02 (£450) tower air purifier and the Dyson Pure Cool Link DP01 (£350) desk air purifier both come from Dyson’s air cooling, heating and cleaning range and sport the recognisable appliance-with-a-hole-in-it design.

What features should I look for on an air purifier? 

Automatic mode and air sensors

Air purifiers with air sensors sniff out pollutants. They can be set to switch themselves on and set their power levels according to the air quality. 

So if you live beside a busy road and traffic starts to build up, an air purifier with a built-in air sensor will spring to life and start cleaning the air. This can also prove handy in summer if you have hay fever.

Do you suffer from a pollen or dust allergy? Find out which models remove the most pollen and dust from the air: see our air purifier reviews.

Air purifier timers

Air purifiers with timers can be set to switch on and turn off. This is helpful if the purifier doesn’t come with an air sensor. It means you can set it to switch on and start cleaning the air before you get home.

Night mode and air purifiers

Night mode should mean quiet air purification, sometimes with dimmed lights, to help you sleep. But our tests show that night mode isn’t always quieter than the lowest speed setting. So if you can’t sleep with your air purifier set to night mode, try turning the power down a little to see if it makes it any quieter.

Smart air purifiers

Smart air purifiers can be set from your phone. Easy-to-install apps allow you to link to the purifier. As well as being used to set the machine, the apps also show the air quality in your home.

The Dyson Pure Cool Link TP02 (£450), the Dyson Pure Cool Link DP01 (£350) and the Blueair 480i (£629) are all smart purifiers. 

Go to our air purifier reviews to find out which apps and smart functionality we liked best.

How much do air purifiers cost?  

You can buy air purifiers for little more than £100 and prices go right up to more than £600. But to be confident you're buying an air purifier that does a good job of cleaning the air effectively, you’re likely to need to spend at least £200. 

But spending this much doesn’t guarantee you’ll end up with a great machine. We’ve tested models costing £450 that are less effective than purifiers that are £200 cheaper.

Best air purifiers 

The best air purifiers will clean the air in your home quickly without making too much noise. But you can also pick a purifier based on the specific allergens or pollutants you want removed. Here are a few: 

Best air purifiers for hay fever

85%
£200.00
Reviewed

This air purifier does a great job of clearing pollen particles from the air. So, if hay fever routinely ruins your summer, it could really help you. It’s our third best air purifier for trapping pollen, and our joint-top air model overall. It’s also fairly cheap as far as air purifiers go.

84%
£699.00
Reviewed

This air purifier did a terrific job of removing pollen from the air in our tests, making it a great choice for hay fever sufferers. It has an LED digital display, a timer, a night mode, an automatic mode and three fan speeds. It’s also controllable via wi-fi from a smartphone app. Surprisingly, though, for a model at this price point, it doesn’t give you air quality feedback.

80%
£349.00
Reviewed

Not only is this the most stylish air purifier we’ve ever tested, it’s among the best we’ve tested when it comes to trapping pollen particles. It’s also very energy-efficient. However, in terms of features it’s fairly basic.

Best air purifiers for smoke particles

84%
£699.00
Reviewed

This air purifier removed plenty of smoke particles from our test chamber, so it’s a good one to choose if you’re often exposed to second-hand smoke. Its features include an LED digital display, a timer, a night mode, an automatic mode and the ability to control it from the Blueair Friend app. It doesn’t give you air quality feedback, though.

81%
£499.00
Reviewed

Another winner from a brand that’s produced several Best Buys. It’s fantastic at capturing dust particles – and at capturing other types of particles, such as smoke and pollen, too. It captured more than 90% of the nasties we pumped into our test chamber. But be prepared for the fact that it’s tricky to remove and replace the filter.

80%
£349.00
Reviewed

This is an attractive air purifier, but it’s not all style over substance as it’s one of the best we’ve tested at capturing smoke particles. It’s also very frugal when it comes to energy use. It’s noisier than we’d like, though.

Best air purifiers for pollution (dust)

85%
£200.00
Reviewed

This air purifier does a great job of clearing pollen particles from the air. So, if hay fever routinely ruins your summer, this air purifier could really help you. It’s our third best air purifier for trapping pollen, and our joint-top model overall. As far as air purifiers go, it’s also fairly cheap.

84%
£699.00
Reviewed

This air purifier trapped more dust particles than any other air purifier in our test, so it’s a good one to pick if you’re concerned about pollution – if you live near a busy road, for instance. It’s a smart air purifier, controllable from your phone. It’s very quiet on the low fan speed, but loud on the high fan speed.

80%
£349.00
Reviewed

This air purifier does a superb job of trapping dust particles, and without using much energy in the process. It’s a pretty air purifier, too – forget the boxy, radiator-like appliances you might be used to seeing. On the downside, it’s noisy.

We don’t specifically test for traffic pollution, but we test whether they can capture particles of a similar size: 2.5 microns (µm). Choose one that scores well for trapping dust, as this should also filter out the harmful PM2.5 particles. Also choose one that has a carbon filter, because the particles are only one aspect of traffic pollution: gases such as No2 are also an issue.

Air purifiers compared

Blueair Pure 221, £349

Size: It measures 52 x 32.7 x 33.6 cm, which is medium to large.
Features: Three fan speeds
Number of filters: Two

The Blueair Pure 221 is the prettiest air purifier we've ever seen. You can choose from a range of fabric pre-filters in different colours, including yellow, pink and blue. But it also has fewer features than some of its rivals, including the cheaper ones.

Does its air purifying make up for its lack of extras? Read the full Blueair Pure 221 review.

Philips 2-in-1 Air Purifier and Humidifier, £480

Size: It's large (68 x 48 x 28cm) so make sure you have the space for it.
Features: Four fan speeds, smart connectivity, timer, night mode, air quality sensor, automatic mode, Hepa filter
Number of filters:
Three

The Philips AC3829/60 2-in-1 is among the most expensive air purifiers we've tested, and it comes with a range of interesting features. It doubles up as a humidifier, can be monitored with a smartphone app, has General, Allergen and Sleep modes and gives you real-time pollution data.

But none of that matters if it can’t do its primary job well. Read the full Philips 2-in-1 Air Purifier and Humidifier review.

Vax AC02AMV1, £250

Size: This cylindrical air purifier is 52cm tall and is designed to stand on the floor in your room.
Features: Three fan speeds, remote control, timer, two-year warranty, night mode, air quality sensor, automatic mode, Hepa filter
Number of filters: One

This air purifier trumps many pricier models in terms of additional features, including having both a night and automatic mode. It even comes with a remote control so you can switch it on and off from the comfort of your own chair. With its pre-filter and Hepa filter being combined, Vax claims that the AC02AMV1 air purifier, also known as the Pure Air 200, is the UK's best purifier. But how did it fare in our tests?

Read the full Vax AC02AMV1 review.

Blueair Classic 605, £699

Size: It's a tall machine: 65 x 50 x 34cm. It's designed with large living spaces in mind.
Features:
Three fan speeds, smart, night mode, automatic mode, Hepa filter
Number of filters:
Three

The Blueair Classic 605 is the most expensive air purifier we’ve tested. It’s smart, has a Hepa filter and you can put it into night mode. But is it really worth a staggering £699?

Read our full Blueair Classic 605 review.

Electriq EAP500HC, £170

Size: It's tall (68.3 x 42.4 x 26cm) and weighs 9kg, so it's made for large rooms.
Features: Five fan speeds, time, night mode, air quality sensor, automatic mode, Hepa filter
Number of filters: Two

The ElectriQ EAP500HC is cheap compared with many you'll see. But that doesn’t mean you’ll be at a loss for features. In fact it has five fan speeds, which is a lot more than the average. It also has a Hepa filter and an automatic mode, but is there a catch?

Read our full Electriq EAP500HC review.

How much do air purifiers cost to run?

We work out how much each air purifier we tested would cost to run, based on being used for 12 hours a day. 

  • £72 per year: approximately how much the most powerful air purifiers are likely to cost.
  • £40 a year: what medium-sized machines are likely to cost.  
  • £26 a year: how much a smaller air purifier is likely to cost.

The smallest and least powerful air purifier we tested cost just £3 a year to run.

To find out more about how much each air purifier we’ve tested will cost to run, check out our air purifier reviews.

Are there quiet air purifiers? 

One in ten owners* we spoke to told us their air purifier affected their sleep. This is why we test the noise produced by models on their highest and lowest power settings, so you’ll know which air purifiers are the least likely to disturb you.

The difference between lowest and highest settings can be the difference between hardly being able to hear the air purifier and an annoying and rumbling whine. For four of the ten air purifiers we’ve tested, the lowest setting was noticeably quieter.

The quietest machines do a very good job of keeping noise to an absolute minimum, both on the lowest and highest setting. We’ve tested some that you can hear when on full power, but we wouldn’t say the noise was intrusive.

*We surveyed 1,337 Which? members in January 2017 and asked them about their experiences of using an air purifier. 

Unless you can try out an air purifier before you buy, the only way you can tell if it's likely to disturb you or not is to read our air purifier reviews.

What is a Hepa filter? 

Air purifiers use an array of filters to capture pollutants. These are often made up of a large particle filter, which can be reused and washed, as well as other finer filters, usually including a disposable Hepa (high-efficiency particulate air) filter. The Hepa filter’s lifetime is limited by how often you use your machine.

Manufacturers often advise that Hepa filters should be replaced every six months to keep air purifiers working efficiently. But if you only use an air purifier every now and then, rather than every day, your filters will last much longer without becoming clogged with particles. Good machines include a filter-replacement indicator, which shows when the Hepa filter is full and ready to be replaced.

New Hepa filters can vary in cost depending on which air purifier you buy. Replacement Hepa filters for the Vax ACAMV101 and the two Dyson air purifiers we’ve tested are £50. Filters for the Philips AC3256/30 cost £30. DeLonghi AC150 filters are cheapest at £20.

How to make air purifier Hepa filters last longer

Manufacturers generally recommend you change your filter every six months, as once it's clogged up it won't be much use to you. That depends on how often you use your air purifier, though. If you don't use it every day, your filters might last a bit longer. 

With some machines (not all), you can also clean the filters to extend their lives, which will save you money. Always follow the manufacturer instructions. If you do vacuum your filter, go gently. Vigorous vacuuming can damage the delicate fibres. And do it outside, to avoid reintroducing captured allergens to your home.

Do air purifiers release ozone? 

There's no ozone emission from air purifiers that use only Hepa filters to cleanse the air. However, ionising air purifiers or products that use UV lights or ozone generators can create ozone because of their electric charge.

What is an air ioniser? 

Instead of using a fan or filter to purify the air, an air ioniser does it by electrically charging air molecules.

An ioniser creates negative ions (a charged particle) and pushes them into the air where they can attach to positive ions (dust, allergens etc). After bonding together, the particles become too heavy to float and will drop to the floor or nearest surface, to be cleaned away.

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