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9 Mar 2022

Coronavirus: can an air purifier protect you?

While there's some evidence air purifiers can reduce traces of airborne viruses, research is ongoing, and you shouldn't rely on one to protect you from Covid-19

At the start of the pandemic, worried people were - understandably - looking for products to reduce the risk of getting Covid-19, and we saw a spike in online traffic for air purifiers.

Nearly two years on and concerns about contracting the virus have dropped considerably. This is largely thanks to a successful vaccination programme that's provided higher protection from serious symptoms, and a greater understanding of the virus itself.

All the same, nobody wants to be unwell if they can avoid it, and avoiding contracting the virus will still be important to many.

But while recent studies have indicated that air purifiers can reduce traces of airborne viruses such as Covid-19, the advice we gave two years ago remains the same: you shouldn't solely rely on an air purifier to filter out coronavirus in your home. Ventilation and good hygiene practices (such as frequent hand washing) remain the most effective ways to protect yourself.

What we do know is that air purifiers can potentially help improve your air quality in other ways. Read on to find out more about the latest research on coronavirus and air purifiers, plus free ways you can breathe cleaner air at home.

Just want to see which air purifiers impressed in our tests? See our round-up of Best Buy air purifiers.

Air purifiers for coronavirus: what do manufacturers say?

Woman on sofa with dog with air purifier

At the start of the pandemic, some air purifier manufacturers implied, or outright claimed, that their machines would protect you from coronavirus. Many have since tweaked their messaging, but in some cases it can still be quite unclear and leave consumers uncertain about the benefits (or not) of air purifiers in relation to Covid-19.

For example, some will state that air filtration can remove SARS-CoV-2 (the virus that causes Covid-19), but caveat that with the message that your primary line of defence against getting infected is to maintain social distancing, wash your hands and wear a mask.

Others will say an air purifier can remove coronaviruses from the air, but refrain from explicitly stating that their machines can remove the coronavirus that causes Covid-19.

Here's what popular air purifier brands state on their websites.

  • AllerAir - states that 'AllerAir Air Purifiers uses its proprietary Super HEPA filter technology to effectively filter viruses like the Coronavirus COVID-19 which is 0.125 micron in size'. Note the use of the word 'like'. AllerAir is not categorically saying its air purifiers filter out the Covid-19 coronavirus.
  • Airpura - states that 'your primary line of defense against getting infected with Covid-19 is to maintain social distancing whenever possible, washing your hands regularly and wearing a mask. According to medical experts, along with the above three essential habits, one should include using an air purifier as an “essential” to ward off concerns about aerosol transmissions'.
  • Blueair - states that while its HealthProtect 7400 air purifier can remove coronavirus particles from the air, it is 'not proven to kill SARS-CoV-2 or prevent transmission of COVID-19. Other Blueair air purifiers have not been tested against SARS-CoV-2.
  • Philips - states that 'an air purifier by itself does not protect against Covid-19 but can be part of a plan to protect yourself and your family by improving ventilation and having clean air'.
Woman and child using air purifier

What does the science say about air purifiers for Covid-19?

At the start of the pandemic, there was - as you'd expect - little to no evidence about the efficacy of air purifiers against Covid-19.

As you'd also expect, there has since been research carried out to investigate just this matter.

In November 2021, a research team at Addenbrooke's Hospital and the University of Cambridge reported that they were able to use HEPA filter/UV steriliser air purifiers to remove most airborne traces of SARS-CoV-2 on surge wards at the hospital. The air purifiers also successfully filtered out other bacterial, fungal and viral bioaerosols (airborne particles containing living organisms). However, it's worth noting they used a HEPA 14 filter (which is medical grade) in the air purifiers, rather than HEPA 13 filters, which are more commonly used in consumer appliances.

And a July 2021 report from the Centre for Disease Control (CDC) in the US also suggested that portable HEPA air cleaners could reduce exposure to SARS-CoV-2 aerosols indoors. However, it focuses on conference rooms, not household environments, and used a simulated environment.

In short, there's a lot more real-world evidence needed - and the results of these research studies don't change our advice about air purifiers and Covid.

Air purifiers and particle filtration

Coronavirus particles do fall within the particle-size range (0.01 microns and larger) that HEPA filters, found in some air purifiers, capture.

An air purifier could therefore capture coronavirus if the device had a particular type of HEPA filter, with an efficiency of 99.95%, and an ultra violet (UV) lamp to then kill coronavirus.

Crucially, though, in the real world, a lot depends on factors such as:

  • the type of HEPA filter you have
  • the size of your room
  • the frequency of air changes in that room
  • ventilation and airflow patterns within the room
  • the state of the filter
  • whether your air purifier is an older model with a fading UV lamp.

Why ventilation is the easiest way to reduce indoor covid-19 transmission

Man opening window ventilation

There is increasing evidence to show that Covid-19 can linger in enclosed spaces and that ventilation is key.

Ventilation is the process of replacing shared, staler air with fresh air from outside. The more ventilated an area is, the more fresh air there is to breathe and the less likely a person is to inhale infectious particles.

The government recommends:

  • Letting plenty of fresh air into your home by uncovering vents and opening doors and windows. If you are concerned about security, noise, or the increased cost of heating from leaving windows and doors open for extended periods, even doing so for short periods while you wrap up warm is still worthwhile.
  • Leaving extractor fans in your bathroom or kitchen running for longer than usual.
  • Leaving windows fully open for a short period after someone working in your home such as a cleaner or tradesperson has left.

The government's advice also recommends that if someone in your home is self-isolating, you should open a window in their room and keep the door to the room closed to reduce the spread of contaminated air to other parts of the household.

Not only can good ventilation help do away with Covid-19 particles in your home, it can also boost indoor air quality more generally. Read our full guide for more on this and other ways to improve your indoor air quality at home.

How else can you reduce your risk of catching Covid-19?

Person taking lateral flow covid test

Covid-19 can be transmitted through respiratory droplets when you're in close proximity to someone, and by touching contaminated surfaces.

To stay safe, follow the latest NHS guidance, including around household visits.

You can also:

  • Wash your hands frequently and for at least 20 seconds
  • Catch coughs and sneezes in a tissue. Avoid touching your eyes, nose or mouth if your hands are not clean
  • Cover your face in crowded indoor settings or in locations where you cannot socially distance.

How an air purifier can help you improve your indoor air quality

When it comes to staying healthy generally, regardless of Covid-19, breathing cleaner air can only ever be a good thing.

If you can increase the flow of fresh air into your home by opening windows, do that. But if that's not a practical option - say, you live on a very polluted street or you suffer from hay fever - then an air purifier can help create cleaner air.

If you suffer from allergies, for example, a good air purifier can trap pollutants such as dust and pollen particles.

What to look for in a good air purifier

If you're going to buy an air purifier, look for one with a HEPA filter. Other filters - including ones with names such as HEPA-type filter - aren't held to the same European Standards as HEPA filters.

Some purifiers come with features that make them easier to use. These may include, for example:

  • Smart features, which let you control the air purifier from your smartphone and/or check pollution levels in your home
  • Auto settings, which prompt the air purifier to spring into action when pollution levels rise.

For more tips on what to look for when buying an air purifier, and to discover the best ones we've tested, check our Best Buy air purifiers and expert buying advice guide.