Do trendy air purifiers really work– and are they worth their eye-watering price tags?
They’re ‘must-have’ gadgets that claim to purge rooms of pollutants, allergens – and even Covid. But...
THEY look like high-tech smart speakers or designer coffee tables and come with grand claims they can purge rooms of harmful pollutants, allergens, bacteria, fungal spores and even the Covid virus. Air purifiers – which suck in a room’s air and filter it before pumping it back out – are must-haves for health-conscious consumers, it seems. A survey from the Government’s Office for Product Safety and Standards found one in 12 Britons owned one.
Many said they made the purchase – often costing hundreds of pounds – due to concerns about air pollution and, of course, Covid. So it’s not hard to see the appeal.
Mounting evidence links poor air quality to chronic illness. Exposure to pollution raises the risk of dementia, heart disease and lung conditions such as asthma, as well as causing pregnancy problems and damage to unborn children.
Emissions curbs on traffic, agriculture and industry have had an impact, with outdoor air pollution levels improving over the past decade. Despite this, in April, Imperial College London researchers found that roughly 97 per cent of UK homes are in areas that suffer from air pollution above limits set by the World Health Organisation.
And, more worryingly, indoor air quality can be much worse than the air outside. Along with fumes that drift in from the street, gases and compounds are released by stoves, ovens, boilers and cleaning products, and even emitted by new furniture. The environmental push to better insulate homes could compound problems – airtight, draught-proof rooms may be more fuel efficient but they also seal in toxins.
And then along came Covid. Initially it was believed the infection spread via close contact or through contaminated surfaces. However, it is now known that transmission is mainly airborne – the virus floats in the air around us, like invisible smoke. Could an air purifier offer a simple – if pricy – solution to both problems?
The answer, according to Alastair Lewis, Professor of Atmospheric Chemistry at University of York, is yes – as long as you choose the right one.
ONE of the main causes for concern in terms of air pollution are solid particles known as particulate matter, or PM. These are graded by size in microns. For example, those rated PM10 – ten microns in diameter – are coarse, larger particles such as dust, mould and pollen that can irritate the eyes and throat. A human hair is roughly 50 microns in diameter, so PM10 is a fifth of this in size and in a high concentration these may be visible.
Particles rated PM2.5 – sometimes referred to as fine particles – are small and more harmful as they can reach deep into the lungs. These are let off by cooking, heating systems, burning candles and air fresheners, to name just a few common sources in the home. Prof Lewis says: ‘Larger particles can cause irritation and coughing but smaller ones are more insidious and can penetrate further into the lungs. As we breathe them in they can trigger conditions such as asthma and other breathing difficulties. They also build up over years of exposure and can cause heart and lung diseases.’
He suggests choosing an air purifier that contains a high-efficiency particulate air (HEPA) filter – which most do – as these are proven to mop up PM10 and PM2.5.
Air purifiers work by pushing air through multiple layers of fine weave fibreglass or polypropylene, a type of plastic, which traps the harmful particles.
‘HEPA filters have a good track record,’ says Prof Lewis. ‘They work by physically trapping particles – a bit like coffee grounds in a coffee filter.’
Gasses are another component of outdoor and indoor air pollution, and getting rid of these presents more of a challenge. ‘Molecules in gasses are smaller, and can pass through HEPA filters – just like the water and flavour makes it through the coffee filter,’ explains Prof Lewis.
Air purifier manufacturers have addressed this and the latest devices include tech, such as activated carbon filters – made from a porous and absorbent material derived from charcoal – aimed at mopping up these toxins.
‘With these newer types we have to take manufacturers at their word,’ says Prof Lewis. ‘They’ll have carried out testing in labs, but how devices perform in the real world can differ.’
So what of the health benefits? A 2003 US study of 30 asthmatic adults who share a home with cats or dogs found running an air purifier in the living room and bedroom improved asthma symptoms for two-thirds of participants.
Other trials found linked air purifier use with better sleep, lower blood pressure and improved lung function. And could they prevent Covid transmission?
Research by Addenbrooke’s Hospital in Cambridge found that using portable air purifiers on wards swamped with Covid patients removed almost all traces of the virus from the air, reducing the risk of transmission. Leeds University is carrying out a trial to see whether purifiers could be effective in schools for reducing Covid infections. Prof Mark Mon-Williams, the project leader, told The Mail on Sunday that air purifiers ‘are effective in removing viral particles from the air, so we can be confident the systems will reduce Covid-19 virus circulation within the classroom’. Prof Lewis says: ‘If you have a respiratory condition such as asthma, or if you’re sensitive to allergens, you might notice an immediate improvement in your symptoms through using an air purifier.’
However, he adds: ‘Most of us don’t notice differences in air quality straight away. The effects of poor air quality are subtle and build up over years to cause more serious conditions.’
Most purifiers are designed to be left on and contain sensors that monitor the air continually, turning the power up and down automatically as and when needed.
Prof Lewis says: ‘If you’re a hairdresser working with chemicals, then it might be running on full blast 12 hours a day. But the average person will find it’s only on for half an hour or so while they’re cooking or cleaning. If pollen is your worry, you’ll need the purifier when the pollen count is high.’
So which air purifiers are worth investing in?
We asked Prof Lewis to look at some of the bestsellers on the High Street and put them to the test...