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Why a HEPA filter doesn’t guarantee your vacuum cleaner will keep allergens at bay

Which? tests reveal that HEPA filters aren't a golden ticket to allergen-free homes

Why a HEPA filter doesn’t guarantee your vacuum cleaner will keep allergens at bay

With hay fever season in full swing and the sun shining, those with allergies and asthma will be looking for ways to keep their coughs and sneezes to a minimum – something that’s particularly important as we strive to protect against the spread of coronavirus.

Keeping allergens like fine dust particles and pollen out of your home is important for relieving allergy symptoms.

And with many of us spending more time at home – perhaps tackling some spring cleaning as a way to pass the time – there’s likely to be more dust getting disturbed than usual.

Plenty of vacuum cleaners claim to be allergy-friendly, and many shout about their HEPA (high-efficiency particulate air) filters, but our independent vacuum cleaner tests show that buying a vac that won’t make you sneeze isn’t as straightforward as it seems.

Here we dish the dirt on filters, using insight from our vacuum dust emissions tests, and explain how to pick the best vacuum cleaner for allergy sufferers.


Vacuum cleaner reviews – compare how models from brands such as Dyson, Vax, Shark and Miele rate for allergen retention, and how cheaper supermarket options compare


Why does vacuuming aggravate allergies?

When you vacuum your home, it unsettles dust, fluff, debris and pollen from carpets, hard floors and other surfaces.

Your vacuum might do a decent job of sucking up most visible dust and debris, but plenty miss the microscopic stuff – or blast it back into the air via the motor exhaust filter – and that’s what aggravates allergies.

You might spot some of the larger dust particles floating in the air after you’ve disturbed them. The human eye can spot dust as little as 25 microns in size.

But it’s the really tiny particles, ones as little as 0.3 microns and invisible to the human eye, that can cause the real problems. These can get flung up into the air during vacuuming and, when inhaled, can cause you to cough and sneeze.

The best vacuums have well-designed suction and filtration systems to capture these particles and keep them safely locked away in the dust container. The worst may suck these particles up but then blast them straight back out into your home through leaky filter housings.


Best Buy vacuum cleaners – make sure you dust-bust your home with a top model


What is a HEPA filter and is it an essential vacuum feature?

Having a HEPA filter is often used as marketing shorthand for claiming a vacuum cleaner is great for allergy sufferers. These filters have to be able to remove at least 99.8% of particles 0.3 microns in size or bigger.

They have multiple layers of criss-crossing fibres, typically made of fibreglass, which work to intercept particles and prevent them from passing out the other side of the filter.

Do HEPA filters work?

It can be tempting to look for a HEPA filter as a sign that the shiny new vacuum cleaner you’ve got your eye on won’t aggravate your allergies, but unfortunately it isn’t that straightforward.

Some vacuum cleaners we’ve tested with HEPA filters have been brilliant at keeping even the smallest particles locked up, but others haven’t been so great.

There are also plenty of vacuum cleaners we’ve tested with excellent filters that aren’t HEPA, so it’s not necessarily a must-have for great filtration.

A key factor is how well fitted the filter is, and how carefully sealed the airways are within the vacuum cleaner. A poorly fitted filter will let some air pass around it instead of through it, letting unfiltered particles escape into the air again via the exhaust.


Each of our top five vacuum cleaners for 2020 has an excellent filtration system that will keep microscopic dust particles at bay.


How will I know if a vacuum has a good filter?

With so many vacuum cleaners making claims about filtration, it can be difficult to know which one will really keep your allergies at bay. That’s where our tests come in.

A vacuum cleaner that sucks up 99.8% of particles might sound impressive, but in our filtration tests such a score would only get an average three stars out of five for allergen retention.

This is because that remaining amount is where all the really pesky tiny particles are that can cause you problems, so it may sound like a small difference but it can make a big impact.

The graph below shows how many particles a five-star rated vacuum cleaner filter will let through compared with a three-star and one-star rated model:

Best vs worst vacuum cleaner

So, depending on the quality of your vacuum cleaner, you could be breathing in a vastly different amount of microscopic dust particles.

That’s why our tests are so important. We measure the dust particle size and concentration, both going into and coming out of the vacuum cleaner, to measure exactly how effective the filtration system is at retaining dust particles large and small.

Find out more in our full guide to how we test vacuum cleaners.

Bagged or bagless: which is better for allergy sufferers?

The choice between a bagged or bagless vacuum cleaner can be an important one when thinking about how to avoid aggravating your allergies.

While some bagless vacuums are very effective at keeping dust and allergens locked up, that can all go to pot when it comes to emptying them.

When we measured dust emissions while emptying a selection of bagged and bagless vacuums, including ones with ‘hygienic’ emptying systems, we found that bagged models were better at preventing dust escaping.

Bagless vacuum brands argue that vacuums with disposable dustbags mean ongoing costs (and waste), and that they lose suction as they fill, although our tests show that this isn’t the case for all bagged models (and some bagless vacs lose suction as they fill too).

If you want to go bagless, some brands – and Allergy UK – advise emptying bagless vacuums into a bag outside while wearing a mask and gloves, to minimise issues, although this could be a bit of a faff.

Corded or cordless?

There are good options for allergy sufferers, whether you’re keen on a corded or cordless vacuum cleaner. Our tests have uncovered models that keep allergens at bay among both types.

Bear in mind that most cordless vacuums, apart from a few options from Gtech, Numatic Henry and Halo, are bagless, so you will have to contend with dust when emptying them to some degree.

They also often have smaller capacities compared with corded models, particularly the bagless options, so you’re likely to need to empty them more often. And on models with really tiny dust containers, debris can get stuck too.

Get the inside track on the best corded vacuums and the best cordless vacuums to consider.

Vacuums designed for allergy sufferers

Vacuum cleaners that make claims around being good for allergy sufferers usually focus on features such as extra filtration and hygienic emptying.

Here are some models that offer features aimed at allergy sufferers:

Numatic Henry Allergy vacuum, £200

The Henry Allergy HVA 160-11 is a twist on the classic red Henry vacuum from British brand Numatic. It comes in an airy pastel blue colour and has a higher-spec filtration system than the standard model, combining HEPA and TriTex filters with HepaFlo filter dust bags. Numatic claims the filters and bag help to capture even the tiniest of dust particles.

The large dust capacity and disposable bag design should help you keep your distance from dust. But does this vacuum do a good job of sucking it up and are there any ways for dust to escape?

Check our full Henry Allergy vacuum review for our independent verdict.

Dyson Small Ball Allergy, £200

Dyson said it was no longer developing new corded vacuums back in 2018, but then it duly launched this updated Dyson Small Ball Allergy model earlier this year.

The ‘remastered’ version of its Small Ball vacuum has a washable lifetime filter and features the ‘one-click’ bin emptying design found on V10 and V11 cordless vacuums. This allows you to empty the container directly into the bin and aims to minimise the problem of the dust cloud.

See our full Dyson Small Ball Allergy review to find out if it’s a good pick for allergy sufferers.

Halo Capsule cordless vacuum, £250

The Halo Capsule is the first model from new brand Halo. It doesn’t make specific allergy claims, but it’s one of the few bagged cordless stick vacuum cleaners available, so it could be a good option if you’re keen to go cordless but want the dust-distancing benefits of a bagged vacuum.

It holds more dust than many rival cordless models too, so you’ll have to make fewer trips to the bin. And with a supply of 52 replacement bags included, you won’t feel too much of a pinch from replacement costs.

See our full Halo Capsule cordless vacuum review to get our verdict.

Latest vacuum cleaner reviews for 2020

We test corded and cordless vacuum cleaners regularly so you can find out how the latest models compare with the competition.

Our most recent results are just in and listed below, including the first-ever cordless vacuum cleaner from Miele, the Halo Capsule, the latest Shark vacuums and some cheap Bush models.

Click on the individual links to see our reviews:


Air purifier reviews – find out if an air purifier can help with allergies

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