Best air purifier – improve indoor air quality and reduce allergens

The best air purifiers to remove dust, pollution and allergy-causing particles from your home...
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  • Many people have been waking up to the fact that, without one of the best air purifiers, the air quality in their homes can be very poor. In fact, research has shown that the air indoors that we breathe every day is often worse than that outside on all but the most polluted streets. This is because particles from traffic fumes, pollen and more are pulled in as we enter the front door or open a window, and there often isn’t enough ventilation to remove them.

    This not only opens us up to the ill-effects of excess dust and pollution but means that chemicals from cleaning products, fresh paint, new furniture and cooking can’t escape either. If you are one of the millions of allergy sufferers, then you will know how much poor air quality exacerbates symptoms – damned if you open a window, but also vulnerable to anything trapped inside if you don’t.

    But there’s good news – having an air purifier in the home can make a huge difference.

    You may think that regular cleaning and vacuuming will keep the problem of bad air at bay, but this alone isn’t enough to eliminate anything smaller than dust particles. A dedicated air purifier will thoroughly clean the air throughout your home and, if you pick a good one that’s the right size for the room, you will really start to notice the difference.

    Read on to find out which of the best air purifiers is best for your circumstances and space and, if you’re also looking to defeat dampness, take a look at our roundup of the best dehumidifiers.

    The best air purifiers in 2021

    1. Blueair Blue 3210

    Best air purifier overall

    Blueair Blue 3210 air purifier

    Credit: Blueair

    Power: 10W
    Speeds: 4
    Room size: 17m2
    Smart?: No
    Noise: 18-48dB
    CADR: 184 m3/hr
    Dimensions: 42.5 x 20 x 20cm
    Weight: 1.6kg

    Reasons to buy

    • Energy-efficient
    • Quiet
    • Easy to set up and use

    Reasons to avoid

    • Only good for smaller rooms
    • No smart features

    If you’re looking for a quiet and unfussy air purifier that will fit into smaller spaces, then the Blueair Blue 3210 is ideal. Perfect for bedrooms or a home office, the Scandi-style machine is super-easy to set up and use.

    To get started, you simply need to plug in the air purifier and tap the top control until you reach your desired setting. These include an Auto mode that uses the in-built sensor to clean the air in a space optimally, Night mode (reducing noise, fan speed and LED brightness), Everyday mode and Boosted mode. These last two do what they say on the tin, quietly toiling away in the background or working a bit harder, respectively.

    The light on the front changes colour to indicate current air quality, whether good, moderate or polluted. It will turn red when it’s time to change the filter, recommended around every six months.

    Working in a room of around 17m2, the Blueair Blue 3210 will change the air in the space five times an hour, with this going down to about twice an hour in a room of 43m2. So basically, it should be placed in a smaller room to get the most out of the device. In return, it works very efficiently, using just 2W of power on its lowest setting (up to 10W).

    The Scandi-style pre-filters are the real star here, though, giving you a choice of the arctic trail (dark grey) – included – winter reed (light grey), archipelago sand (pink), aurora light (green), and night waves (blue). These don’t just look pretty, either, catching larger particles and extending the life of the primary filter inside. To clean, you can just vacuum the outside or pop them in the wash.

    Ideal Home rating: 4.5 out of 5 stars | read our full review of the Blueair Blue 3210 Air Purifier

    2. Levoit Core 300 Air Purifier

    Best small air purifier

    Levoit Core 300 Air Purifier

    Credit: Levoit

    Power: 33W
    Speeds: 3
    Room size: 40m2
    Smart?: No
    Noise: 24-48dB
    CADR: 187 m3/hr
    Dimensions: 36 x 22 x 22cm
    Weight: 3.4kg

    Reasons to buy

    • Can clean larger rooms
    • Quiet on lowest settings
    • Customisable filters

    Reasons to avoid

    • No smart features
    • No air quality sensor

    Another of our favourite small air purifiers, the Levoit Core 300, is ideal for those who don’t feel the need for smart home compatibility. Quiet on its lowest settings, it can clear an impressive area of 40m2, delivering a CADR (clean air delivery rate) of 187 m3/hr with its patented QuietKEAP technology.

    The controls are on top of the air purifier, allowing you to change the fan speed (low, medium or high), set a timer (2, 4, 6, or 8 hours) for auto-shutoff, or put it in night mode. This means you can have the machine in your bedroom without worrying about wasting energy or the LED lights keeping you up.

    One of the best things about the Core 300 is the customisable filters. The original filter is included, but you can also purchase filters specialising in pet allergies, toxin absorption, or mould and bacteria removal. When any of these need replacing, the check filter indicator light will activate, with it recommended you switch filters every 6-8 months.

    Ideal Home rating: 4 out of 5 stars

    3. Philips Series 3000i Connected AC3033/30

    Best air purifier for large rooms

    Philips Series 3000i Connected AC3033/30

    Credit: Philips

    Power: 55W
    Speeds: 3
    Room size: 104m2
    Smart?: Yes
    Noise: 34dB
    Dimensions: 64 x 29 x 29cm
    Weight: 9kg

    Reasons to buy

    • Capable of cleaning large spaces
    • Compatible with Alexa
    • Easy to remove and long-lasting filter

    Reasons to avoid

    • Large and heavy

    An air purifier for heavier jobs, the Phillips Series 3000i Connected air purifier promises to clear the air in spaces up to 104m2. For example, a 20m2 room can completely clean the space in 6-8 minutes, with an impressive CADR of 520 m3/hr.

    The auto mode makes use of the built-in sensor and adjusts its speed accordingly. A handy digital display on top gives you real-time information on air quality levels, including allergens, particles and gas that are circulating. You can also access this information via the app to connect to Alexa for voice control.

    The three-level filter has been handily combined into one removable unit, making it easier to change things when needed. This won’t be very often, however, with an estimated lifetime of 36 months.

    The drawback of the 3000i Connected is its size, measuring 64cm tall and 9kg. This makes it one of the more difficult air purifiers on this list to move around, so you should make sure it can have a permanent home before you buy. Thankfully, Phillips has thought about putting such a large machine in people’s living spaces and made an effort to make it look somewhat stylish.

    Ideal Home rating: 4 out of 5 stars | read our full review of the Philips Series 3000i Connected AC3033/30

    4. Dimplex DXAPV3N

    Best budget air purifier

    Dimplex DXAPV3N air purifier

    Credit: Dimplex

    Room size: 28m²
    Weight:
    1.4kg
    Dimensions:
    13.3 cm (H) x 24.8 cm (L) x 33.3 cm (W)
    Noise levels: 40-50dB

    Reasons to buy: Great for a budget and looks inconspicuous
    Reasons to avoid: It’s not that suitable for 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 it 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. It sounds like a fan in both settings, 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 the test, so, surprisingly, 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 the test.

    The test results bore out these. 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 the 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 rating: 4 out of 5 stars

    5. IKEA Fornuftig

    Best air purifier for design

    IKEA Förnuftig air purifier

    Credit: IKEA

    Room size: 10m²
    Weight: 
    3.9kg
    Dimensions: 36 x 13 x 57cm
    Noise levels: 28-50dB

    Reasons to buy: great design, affordable, can be mounted on the wall
    Reasons to avoid: gas filter sold separately

    A gorgeous air purifier from IKEA and designer David Wahl, the IKEA Förnuftig has caused quite a stir since being released. This piece of home tech puts design first, with the option to either place it on the floor (as pictured) or mount it to the wall. It looks great either way, but our preference is mounted, where it could be mistaken for a piece of décor.

    The purifier comes equipped with a particle filter that claims to filter around 99.5% of small airborne particles (PM2.5), including dust, pollen and a whole host of other nasties. You can also fit a gas filter that takes more dangerous pollutants such as formaldehyde and unpleasant smells out of your indoor air – though unfortunately, this is sold separately.

    The IKEA Förnuftig has three fan speeds, which is pretty standard for something at this price point, and the lightweight and sleek design makes up for some shortcomings in performance.

    How to choose the best air purifier

    Blueair Blue 3210 on floor with dog

    Credit: Blueair

    Do air purifiers 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.

    Are air purifiers effective?

    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. But, unfortunately, 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 beneficial if anyone in the family has asthma or allergies.

    Where to place an 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 remove smells?

    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 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 filters, 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 is great for microscopic 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 measure 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, 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 testers Caramel and Caroline have decades of experience in reviewing technology products between them. 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, Caramel has 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. So 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. Caramel tested the room’s initial air quality for each air purifier and then tested it again after she had used the air purifier 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 air quality benchmarks. These are particles measuring no more than 10 microns and no more than 2.5 microns.

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