How to buy the best air purifier
The best air purifiers will do a great job of cleaning the air in your home. But there are also plenty of air purifiers that struggle to tackle common household allergens – including some expensive models.
We've put the most popular air purifiers on the market through our tough lab tests so we can tell you which are the best air purifiers.
Not sure which type of air purifier to buy? Scroll down to find out if an air purifier is right for you, the types available, and how much you should expect to pay.
Best air purifiers
The best air purifiers will clean the air in your home quickly without making too much noise or using too much energy. The worst will be significantly slower, trapping far fewer particles in the same time period, and potentially making more noise and using more energy in the process.
Some air purifiers are great all-rounders, while others are better at tackling one type of pollutant than another. If you've got hay fever, for example, your priority might be picking an air purifier that's great at trapping pollen.
Best air purifiers for hay fever
Best air purifiers for smoke particles
Best air purifiers for pollution (dust)
Tables last updated January 2021.
We don't specifically test with traffic pollution particles: we test with dust, pollen and smoke particles, as these are common household allergens. However, an air purifier which performs well in our dust tests is likely to also do a good job of trapping harmful PM2.5 particles which are of a similar size to dust: 2.5 microns (µm).
Particles are only one aspect of traffic pollution, though : gases such as No2 (Nitrogen dioxide) are also an issue. If you can, buy an air purifier with a carbon filter, as carbon filters are designed to trap gases.
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?
An air purifier shouldn't be your first line of defence against air pollution.
The best way to control indoor air pollution is to eliminate the source of the pollution. Minimise your use of products that cause indoor air pollution, such as chemical sprays. Keep humidity under control, so that biological contaminants don't thrive, and employ good hygiene practices.
The second best way is to ventilate, particularly when you've just carried out an activity that causes pollution.
If you already do that, you could also buy an air purifier, to supplement the good work you're already doing.
And, if you suffer from allergies, an air purifier could be a particularly 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 particles. 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 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 or pollen.
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.
Tower air purifiers
Tower air purifiers are tall, often cylindrical, and can be as large as a kitchen bin. They can be powerful enough to work in large open-plan spaces in the home.
Air purifiers that double as humidifiers or heaters
A couple of air purifiers have other functions, such as heating or humidification.
Dyson is a famous brand, but our tests have shown time and again that big name is no guarantee of a great product – check our reviews before you buy.
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.
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. Or try running the air purifier in your bedroom all day, with the doors closed, and switch it off at night, so at least the air in your room will be much cleaner at the point you try to sleep.
Smart air purifiers
Smart air purifiers can be controlled from a paired smartphone. Some of the accompanying apps offer other useful features - information about the air quality levels in your home, for example.
Air purifiers for coronavirus
You might be wondering if an air purifier can tackle coronavirus. There's no scientific evidence to show that an air purifier can protect you from Covid-19. To protect yourself and others, make sure you follow the latest NHS advice.
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.
How much does an air purifier cost to run?
Obviously the cost of running an air purifier will depend on a number of factors, including how much energy it uses, how often you run it and how much you're paying for energy.
As a rough guide, though, if you were to run your air purifier for 12 hours a day, every day, it could cost you between £20 a year and about £160 a year. That's based on the assumption that electricity is 14.4 pence/kWh (kilowatt-hour).
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.
Blueair Classic 405 Air Purifier, £499
Size: It's large (60 x 50 x 28cm) so make sure you have the space for it.
Features: Smart connectivity, night mode, Hepa filter
Number of filters: One
We've been impressed by Blueair air purifiers in the past, so was the 405 up to the task when we pitted it against a barrage of dust, pollen and smoke particles in our test chamber?
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?
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?
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?
Are there quiet air purifiers?
If you have allergies that interfere with your sleep, you may want to run your air purifier in your bedroom at night. But you can only do that if your air purifier isn't going to be horribly noisy. Some air purifiers come with a dedicated night time setting, but they're not always as quiet as you'd hope.
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.
The quietest machines do a very good job of keeping noise to an absolute minimum, both on the lowest and highest setting.
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. Some 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 from about £20 to more than £50 depending on which air purifier you buy.
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.
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.
Do air purifiers release ozone?
Ozone can react with pollutants to alter their chemical composition. If you have a lung condition, ozone can lead to breathing difficulties, wheezing and coughing. Even if you're healthy, ozone can irritate your airways.
You don't need to worry about an air purifier which uses a HEPA filter alone to clean the air. However, ionizing air purifiers, or products that use UV lights, could give off ozone because of their electric charge. If you can, look for one that states that it does not create ozone. You should actively avoid any that describe themselves as 'ozone generators'.