Many people are waking up to the fact that the air quality in our homes can be very poor. This not only opens up to extreme symptoms during allergy season, but also to ill-effects from excess dust and pollution that enters our space. Having an air purifier in the home can make a massive difference.
Research has shown that the air we breathe every day is often worse than that outdoors on all but the most polluted streets. Particles from traffic fumes, pollen and more is pulled in as we enter the front door or open a window and there often isn’t enough ventilation to remove them. The chemicals in cleaning products, fresh paint, new furniture, cooking fumes, dust and other nasties only add to the problem
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You may think regular cleaning and vacuuming keeps the problem of bad air at bay, but it can’t deal with anything smaller than dust particles. A dedicated air purifier will thoroughly clean the air and, if you pick and good one that’s the right size for the room, you’ll notice the difference.
Read on to find out how to choose the best air purifier for your space.
Read next: Looking to defeat the damp? Take a look at our roundup of the best dehumidifiers
The best air purifiers to buy in 2021
1. Blueair Blue Pure 411
Best air purifier overall
Weight: 2.74 kg
Dimensions: 20.3 cm (H) x 20.3 (L) x 42.4 cm (W)
Noise levels: 17-46dB
Reasons to buy: Affordable, comes with a washable filter
Reasons to avoid: Cold air comes out the top, so it could turn the room chillier
The small Blueair is hard to fault for the price. It’s one of the most affordable air purifiers on the market, compact, good-looking and performance is excellent. It’s a lightweight cylinder that can stand on the floor or a bedside table, measuring 424 x 203 x 203mm.
The coloured fabric cover isn’t just for show. It’s a washable pre-filter that removes larger particles, which in turn prolongs the life of the finer filters inside. The main filter should last for 6 months. The machine alerts you when it’s time for a new one and you can subscribe to get them at the right time.
The main HEPASilent filter combines electrostatic and mechanical filtration to remove airborne contaminants down to the size of viruses. It will also trap pollen, dust, pet dander, mould spores, smoke, allergens and bacteria. Activated carbon pellets remove odours, gases and VOCs.
There are three speeds, with a simple button on the top that you press to cycle between them. It’s quiet at 17-46dB and has been awarded the Quiet Mark. The lowest speed is almost silent, you forget that it’s on; the higher speeds sound like a fan.
It’s designed for a room of up to 15m² (with five air changes per hour) so it’s perfect for even a pretty large room. Use it in a bedroom, shut the door (a great idea for fire safety anyway) and your lungs will benefit from clean air while you sleep. It has a Clean Air Delivery Rate (CADR) of 180m³/h for smoke and 200m³/h for dust and pollen.
The Blueair 411’s test results were outstanding for its price and size. It removed 96 per cent of PM2.5 and 99 per cent of PM10 particles in an hour, making it more effective than most of the competition, including models costing twice as much.
Ideal Home’s rating: 5 out of 5 stars
2. Blueair Classic 480i
Best air purifier for large rooms
Weight: 15 kg
Dimensions: 590 x 500 x 275mm
Noise levels: 32-52dB
Reasons to buy: Extremely powerful, it can be used for huge areas
Reasons to avoid: At £629, this is super pricey, so think twice before investing in one
This is the priciest air purifier on test but also the most powerful and effective. It cleans much more than a roomful of air and would be suitable for a large open-plan space, an entire flat or a workspace.
Workspace springs to mind because of the 480i’s industrial looks. It’s a large (590 x 500 x 275mm) metal box, like a tower PC but bigger, or like an aircon unit. The flat top is handy: have this in the home and you’ll soon put a plant on top of it.
One side of the top flips up to reveal a series of discrete controls, but after the initial setup you rarely need to access them for two reasons. Firstly the 480i has an automatic mode, which detects air quality and adjusts its power level accordingly. Secondly, it uses Wi-Fi to connect to your internet, so you can monitor air quality and control the machine via app from anywhere. There’s also a sleep timer.
We tested the version with the optional SmokeStop filter, which uses electrostatic charge to help it capture fine particles such as tobacco smoke and traffic fumes. For around £50 less you can get the machine with a particle filter and no SmokeStop.
There are three fan speeds and noise is not bad at 32-52dB, for which it was awarded a Quiet Mark. Only the top setting is loud and the auto mode is ideal because it only goes full blast when air quality is poor. It’s designed for rooms up to 40m², the size of a small flat or a large open-plan space, with five air changes per hour. It has CADRs of 476m³/h for smoke, 510m³/h for dust and pollen.
Performance was excellent. In a large room it removed 96 per cent of PM2.5 and 99 per cent of PM10 particles in an hour. With that and its high capacity, it’s tempting to give this air purifier top marks but its price, bulk and looks mean it’s not right for many homes, so we had to dock it a half mark. But if you want a clean air workhorse then look no further.
Ideal Home’s rating: 4.5 out of 5 stars
3. Dyson Pure Cool Me
Best purifying fan
Dimensions: 40.1 cm (H) x 24.5 cm (W) x 24.5 cm (D)
Noise levels: 44-61dB
Reasons to buy: Dyson’s engineering ensures clean, filtered air
Reasons to avoid: It’s louder than other purifiers, so not ideal for workspaces
Dyson doesn’t pitch the Pure Cool Me as an air purifier that cleans all the air in a room, so it doesn’t give figures for recommended room size, air changes per hour or CADR. Instead it is billed as a fan that cleans the air in the personal space around you. The idea is that it sits on your desk or bedside table and directs filtered air straight at you: your personal clean air bubble.
The industrial design is similar to Dyson’s larger Air Multiplier fans, but they don’t filter all the air: air that passes through the machine’s fan is filtered but then the clever design multiplies that air by pulling more (unfiltered) air along with it.
The design is cute. It measures 401 x 254 x 274mm. You choose the angle of airflow up and down manually with your hand but there’s a small remote control for everything else. This attaches magnetically to the front when not in use. You’re a bit lost without it: only able to turn the fan on and off.
With the remote you can choose fan level (0-10), oscillation (off or 70 degrees), sleep timer (30 mins to 8 hours) and see how much life the filter has left. There is a filter change alert and its life is given as a year if used 12 hours a day.
It uses an activated carbon and glass HEPA filter and noise is 44-61dB. Unsurprisingly, it sounds like a fan.
We tested the Dyson just like the others, to see what impact it had on air quality in an average-sized bedroom. The results weren’t terrible: it removed 67 per cent of PM2.5 and 79 per cent of PM10 particles in an hour. This means that despite not setting out to purify the air in the whole room, it does a better job of it than some.
The focussed beam of air is pleasant and cooling in the summer. So if you’re in the market for a fan anyway, and your budget stretches to the Dyson, it’s a good buy. It would be lovely on a bedside table or desk in the summer. But if your priority is air purification then you can get something better for much less.
Ideal Home’s rating: 4 out of 5 stars
4. Dimplex DXAPV3N
Best budget air purifier
Dimensions: 13.3 cm (H) x 24.8 cm (L) x 33.3 cm (W)
Noise levels: 40-50dB
Reasons to buy: It’s on a discount right now, so great if you’re on a budget
Reasons to avoid: It’s not that suitable to larger rooms
If you’re on a really tight budget, this slim air purifier is better than no air purifier at all. It’s the size of a cookbook stood upright (333 x 248 x 133mm) so doesn’t take up much space on a bedside table. The control is simply a lever on the right-hand side that chooses between the two speeds and off.
Noise levels are 40-50dB. On both settings it sounds like a fan but it’s a white noise you could easily ignore and go to sleep with. Filter life is quoted as 2,000 hours of use but there’s no filter change indicator.
Filtration is HEPA and carbon but the size of the filter is small compared with others on test, so it’s surprising that it claims to be suitable for a room measuring up to 28m². The technical data reveals that this is based on 1.75 air changes per hour. So if you want 5 air changes per hour, your room would have to be just under 10m², which sounds more realistic. CADRs for smoke, pollen and dust are 80, 89 and 79m³/h, much lower than others on test.
These were borne out by the test results. It removed 57 per cent of PM2.5 and 66 per cent of PM10 particles in an hour. This makes it the least effective air purifier on test but it’s also by far the cheapest. If you have a small bedroom then using the Dimplex would improve air quality. But we’d recommend the Blueair 411 as well worth the extra expense.
Ideal Home’s rating: 4 out of 5 stars
5. Philips Series 3000i AC3829/60
Best portable air purifier
Weight: 8.42 kg
Dimensions: 80 cm (H) x 49 cm (W) x 39 cm (L)
Reasons to buy: Doubles as a humidifier. Track, monitor and control it with the Air Matters app
Reasons to avoid: Its industrial look may seem out of place in the living room
Admittedly it’s the only air purifier here on wheels, but they are handy. The Philips is a similar size to the Blueair 480i and again has an industrial look and feel: like a home aircon unit or a large fan, humidifier or dehumidifier. In fact, the Philips is also a humidifier.
It looks curvier and cuter than the Blueair but there’s a grille on the top, so you can’t put things on there. It’s on castors, which makes it much easier to move around – from room to room or just moving it out of the way when you’re vacuuming.
Again it’s Wi-Fi and app connected, giving you remote control, air quality monitoring, child lock, a sleep timer of 1-12 hours and more. Noise is rated at 64dB but that’s clearly at the highest of the four fan speeds: on the lowest speed you can’t hear it. The auto mode is great, so it’s only loud when necessary.
The Philips is billed as suitable for a room size of up to 80m², which is large. There’s no figure given for how many air changes per hour. However, it does say: “In a room of 20 m², it can purify the air in less than 10 minutes, so the air gets cleaned more than 6.5 times an hour.”
It uses dual filters: HEPA and activated carbon pellets. CADR is given as 310m³/h and humidification 600ml/h. We didn’t use the humidifier while testing air quality.
In our test in a large room it removed 87 per cent of PM2.5 and PM10 particles in an hour, which is good, but not as good as the Blueair 480i’s performance in the same room. It’s a pretty good workhorse for large spaces.
Ideal Home’s rating: 4 out of 5 stars
Read next: Expert reveals 9 simple ways to reduce allergens in the home
How to choose the best air purifier for you
Do air purifiers really work?
Yes. Read the reviews because some are better than others and you should pick the right machine for your room size. But yes, they remove everything from dust to very fine particles from the air, quietly and invisibly. In the summer, opening doors and windows for ventilation is a great way to improve indoor air quality – unless you live on a really congested road. But in colder months an air purifier is just the ticket.
What is an air purifier good for?
Improving indoor air quality is beneficial for anyone. Given a choice between walking down a polluted main road or a side road next to a park, you’d pick the latter every time. Indoor air quality is under threat from wafted-in pollutants, allergens, dust particles, candles, open fires, Volatile Organic Compounds (VOCs) from cleaning products and “off-gassing”. This is a process where VOCs are released from paints and plastics for years. So using an air purifier is like taking the leafy side of the road. They can be especially helpful if anyone in the family has asthma or allergies.
Where should I place my air purifier?
The machine cleans and circulates all the air in the room. So the only thing that matters is not to place it too close to the wall or furniture. You want 10cm around it on all sides to guarantee airflow in and out of the air purifier. Room-wise, if you pick one room, pick the bedroom. You spend about a third of your life in there, hopefully with the door shut (which is better for fire safety, too). The clean air will help promote deep sleep, as well as being good for your health.
Do air purifiers make your house smell better?
Air purifiers that use activated carbon filters will remove the Volatile Organic Compounds (VOCs) that cause smells. That could be a musty smell or the particulates from a scented candle or aerosol.
How long does it take for an air purifier to clean a room?
It depends not just on the air purifier but how big the room is. Measure your floor space and look for a machine that promises to clean the air in a room of that size five times an hour. Which means it filters all the air in the room once every 12 minutes. Machines sometimes claim to clean large spaces but then they only promise to clean the air a couple of times an hour.
How much should I spend on an air purifier?
For one room: £150 and look at the Blueair 411, which outperforms others that cost more. Budget £500-700 if you want to clean the air in a much larger space.
What are the different types of filter and which do I need?
The more stages of filtration, the better, to remove different sized particles.
- Dust pre-filter – think of air filtration like sifting sand on a beach. You want to remove the large pebbles first with a big sieve before using a finer one. Otherwise, the fine filter gets clogged up.
- HEPA filter – this catches more dust, pollens, other allergens, even bacteria, so you’ll breathe cleaner whether you suffer from pet allergies or hay fever. Our PM10 test results are a measurement of particles no bigger than 10 microns wide.
- Electrostatic filtration – this charges small particles so that they stick more easily to the filters.
- Active carbon – this is great for very small particles from traffic fumes, cigarette smoke and the Volatile Organic Compounds (VOCs) that carry unpleasant smells. They can even remove viruses from the air. Our PM2.5 test results are a measurement of particles no bigger than 2.5 microns wide, which includes much tinier particles.
How do I get the right-sized machine for my room?
Measure your floor space in m². Then pick a machine that promises to clean the air in the room five times an hour. Ceiling heights are pretty consistent so this is accurate enough. If you enjoy maths homework then you can measure the volume of the space in m³ and look at the Clean Air Delivery Rate (CADR) of various machines to see which suits you best.
What else should I think about when buying an air purifier?
Noise if you’re sensitive to it, measured in decibels (dB). If you want a discreet air purifier, consider a machine that’s quiet on its lowest setting. Or one with an auto mode that is quiet unless it needs to scrub the air more, which is unlikely in the middle of the night.
Sleep timers are ok for the bedside but surely it’s better to have a quiet machine that you can leave on, so the air is clean all night.
How we test our air purifiers
Our tester Caramel has decades of experience of reviewing technology products. Writing for, among others, The Evening Standard, The Express, The Guardian, The Independent, The Mail on Sunday, The Sunday Mirror, The Telegraph and The Sunday Times. She’s long been part of the Ideal Home family and knows exactly what you’re looking for in an air purifier.
London’s air pollution, along with two tweens and a dog, meant that the air in Caramel’s house needed a good scrub. She tested each machine rigorously at home, taking into account the size, price, controls, features and noise levels as well as the all-important air purification performance.
Performance was tested using expensive high-end industrial equipment, namely the Met One Instruments Model 804 Handheld Particle Counter. For each air purifier, Caramel tested the room’s initial air quality and then tested it again after the air purifier had been used at its top setting for an hour. Finally, she compared the two sets of results to establish how well the air had been cleaned.
She focussed on the PM10 and PM2.5 figures for our test because these are the ones the World Health Organisation uses as benchmarks of air quality. These are particles measuring no more than 10 microns and no more than 2.5 microns.