A health alert has been issued over some reusable facemasks with evidence that some filter out just 7per cent of harmful bacteria.
The warning comes from consumer experts at Which? after a survey of 15 masks which suggest some offer little or no protection.
Three of the masks, available online and in the high street, were so flimsy that they have been issued with a ‘Don’t Buy’ rating.
These include the Etiquette mask, which is sold by Superdrug, the Termin8 Lightweight Breathable, available at Lloyds Pharmacy and elsewhere, and the Asda White Patterned.
Asda has pulled its face covering from sale as a result of the findings.
Asda has pulled its face covering (left) from sale as a result of the findings. Right, the Termin8 Lightweight Breathable mask did not fare well in the tests
As many as 85 per cent of us aren't washing our fabric face coverings properly in between uses, and 15 per cent have never washed theirs, suggests a YouGov survey from August.
And among those who opt for disposable masks, more than half aren't binning them after use, but re-wearing them multiple times.
UK Government guidelines advise washing reusable masks 'in line with manufacturers' instructions at the highest temperature appropriate for the fabric', while the World Health Organisation recommends washing them 'at least once a day'.
Enzymes in the detergents break down the protective envelope around the virus and so destroy it — they work in the same way as 70 per cent alcohol hand sanitisers.
Washing by hand at lower temperatures also means you are less likely to degrade the material and damage the mask — which could make it less effective as a barrier to virus droplets.
To avoid contamination in between uses, you should store your fabric mask, or your spare disposable ones, in a clean, resealable plastic bag.
Termin8 and Superdrug disputed the findings and said that their masks conform to government guidelines for fabric face coverings and that the guidance doesn’t require them to have bacterial filtration.
Scientists tested the masks for how well they filter bacteria, how breathable they are, and how they fare after multiple washes.
Perhaps surprisingly, Which? found that many of the masks performed better after they were put through a hot wash as this meant the fibres became more compressed.
Which? said reusable fabric face coverings are not designed to block ultra-fine particles such as Covid-19 like a higher-grade medical respirator mask would.
However, they can help because they are intended to help block larger droplets and aerosols breathed out by the wearer, who may be infected but asymptomatic.
In theory, this should help protect the wider community by minimising exhalation of virus particles in enclosed spaces.
Masks with multiple layers were much more effective than single layer versions at filtering particles.
However, the fact they had more layers meant it was more difficult to breathe easily through them.
Which? awarded two of the products tested ‘Best Buy’ status because they were comfortable and breathable without compromising on filtration.
These are the NEQI reusable face mask (£15 for 3), which is available from retailers including Boots and Ocado, as well as Bags of Ethics Great British Designer face coverings (£15 for 3), available at Asos and John Lewis.
Head of Home Products and Services at Which?, Natalie Hitchins, said: ‘With face coverings now such an important part of daily life, they not only need to be durable and comfortable, but also provide effective filtration from harmful particles in order to keep us and others safe.
‘We would urge manufacturers to use our findings to up their game and improve their products.’
The Asos design Palm Print face covering, which costs £12, scored well with a 78% overall rating in the tests