Consumer choice brand Which? has conducted tests on a number of reusable face masks, and has found huge disparities between the percentage of air particles some are able to filter.
Its independent lab test of face coverings found some cloth masks are highly effective at blocking particles, while more basic single-layer masks may not provide much filtration protection after all.
Here is everything you need to know.
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What did the tests find?
For its tests, Which? looked at 15 reusable fabric face coverings of different designs to find out how well they filter bacterial particles.
It found that face masks of similar pricing can be widely different in the amount of bacterial air particles they are able to filter out.
The face coverings that performed best were able to block more than 99 percent of bacterial particles penetrating the mask material, while the worst managed only 7 percent.
Masks with several layers proved better than single-layer masks at filtering particles, and three-layers seemed to be the magic number.
Masks which include disposable filter inserts as the middle are most effective (blocking more than 95% of particles), though the Smart Mask – sold online – manages this without the aid of a disposable filter, making it cheaper and more eco friendly.
Which? also found that washing reusable face covering made them more effective at filtering particles.
"Almost all of the face coverings we tested proved more effective at filtering particles after five hot washes,” it said, “due to the fibres compressing.”
Which face masks are the best?
Which?’s tests found that NEQI Reusable Face Masks are likely to provide the best protection, and awarded the product a satisfaction score of 81 percent.
"This simple, fabric face covering impressed in our tests,” said Which? “The three-layer construction did a good job in our bacterial filtration tests, capturing 80% of particles on the first test and 72% after five washes.
Testers also found the masks – which cost £15 for a pack of three and are available from Boots and Ocado – easy to breathe in and comfortable to wear..
“The mix of cotton, polyester and a touch of elastane (spandex) means this face covering is soft, comfortable and a little stretchy.”
Which face masks were the worst?
At the other end of the scale, Termin8’s lightweight breathable face covering received a score of just 35 per cent – Which? only award the masks one star for filtration efficiency.
They described the mask as “breathable”, but said that because “it's not providing much of a barrier.
"Other reusable face coverings we tested were six times more effective at filtering particles; it was the worst overall for filtration and we recommend you avoid it.”
Which? shared its results with Termin8, which disputed the findings and said its masks conform to government guidelines for fabric face coverings, which don’t require them to have bacterial filtration.
A similar mask from ASDA has been removed from sale as a result of Which?’s findings, which concluded the supermarket’s White Patterned face masks were only “marginally better than no mask at all."
"If you've already gone one of these, it's time to trade up.”
A version of this article originally appeared on our sister title, the Scotsman