Reusable face coverings with claims of germ-killing properties are becoming increasingly common, carrying with them the tempting promise of extra protection for the wearer.
From silver and copper infused masks to snoods with special nano coatings, these hi-tech face coverings claim to attack viruses and bacteria that land on the mask.
This should prevent harmful microbes from penetrating the mask, but also mean they don't stick around on the surface - meaning you might not have to be quite so vigilant about handling and washing your mask.
It's an appealing thought, but can you really trust them?
We asked a microbiologist to examine the scientific claims behind some of these products, including the
Some were promising - we were generally impressed by the Copper Clothing mask, and the EVAQ and Virustatic Shield provide some interesting evidence for their claims.
However, we don't know enough yet about the real-life effectiveness of these products.
People may be lulled into a false sense of security if they think they're walking around with virus-killing covers on their faces.
There are also some safety concerns with the sudden widespread use of antimicrobial fabrics in something that we use on our faces and in close proximity to our airways.
It's important to remember that, while antimicrobial masks may provide some extra protection, good hand and face covering hygiene, and social distancing, remain the most important ways to protect yourself and others.
We picked five different types of reusable face covering which made claims about germ-killing fabrics in some form or other.
Our microbiology expert examined the evidence for their claims. We also tried the masks on to see how comfortable they were to wear, and looked at the small print on washing them and how long they last.
The Virustatic Shield is a snood with an antiviral coating that the manufacturers say blocks, captures, and disables respiratory viruses on contact (including COVID-19).
It's made from a viscose/lycra blend and wraps snugly around the face. Virustatic says you can pull it down to sit around your neck when not in use (usually a no-no for face coverings because of germ transfer).
Virustatic says the snood is the result of 10 years of research and that it's accredited to an international standard for antiviral textiles.
The front page of its website claims 'up to 99% virus protection including influenza and COVID-19.'
The antimicrobial agent that Virustatic uses is a protein called lactoferrin.
Dr Lena Ciric, environmental microbiologist at UCL, says there is evidence that this can be effective in binding to the virus surface and stopping it from replicating.
A number of studies have investigated the possibility of using lactoferrin as an agent against COVID-19. Two showed promising results but have not yet been peer reviewed.
The Virustatic Shield was tested using live influenza virus in 2017 by a leading London University, which hasn't put its name to the study.
The report says that in nine out of 10 cases the trademarked 'Viruferrin' coated viscose blend the snood is made from captured more than 90% of the flu virus, and that it created a barrier for up to 98% of the flu virus. Dr Ciric notes there isn't any evidence for the 'up to 99% protection against SARS-CoV-2 (the technical name for COVID-19)' claim on the website homepage.
When we queried this, Virustatic said that 'there is evidence on both the website and the scientific summary. We are constantly trying to keep the messaging updated whilst balancing translating difficult scientific concepts into understandable language.'
It added that 'the anti-viral coating of the Virustatic Shield disables up to 99% of any infectious material with which it comes into contact, with repeated tests showing that less than 1% of the virus is redeposited on to your fingers or other surfaces.'
It's elasticated and fits snugly, and because it wraps around your head and neck there's less of a chance for air to escape out the sides (though it still felt like breath was coming out the top, as it's not moulded to your nose).
It looks like it could slip down easily but in fact stays in place well, once you've got it situated.
It's relatively easy to get on and off, but you do have to pull it over your head and up around your face, so it's a little trickier if you want to keep your hair neat.
It's quite breathable but the elasticated fabric does press down on your nose.
It's essentially a big bandage around your face, which is quite a striking look, but could be good for winter doubling up as a scarf.
It is only two layers, if you fold it over as instructed, but Virustatic says it's effective even as a single layer covering. The brand says that the three-layer rule doesn't apply to their product because of the antimicrobial fabric.
The rules around washing it are slightly odd: Dr Ciric points out that 'the manufacturer recommends that it is only washed up to three times in total by hand with no detergent,' but it also says it will last for 200 hours.
That is a lot of wear time in between washes and it's unlikely people will stick to it. Plus, the manufacturer warns that the snood may lose its shape slightly in between washes.
The EVAQ mask is a two-layer antiviral face covering made from a polycotton fabric which has a nanotech fabric coating called DiOX D4. EVAQ says this 'has a proven ability to reduce viral loads (including COVID-19) by 99% within one hour of contact.'
The mask has been independently tested by Cambridge University scientists and EVAQ says it conforms to the international standard for antiviral textiles.
This coating is said to create an invisible barrier of microscopic 'spears' that puncture any enveloped virus (such as coronavirus) on contact, which effectively destroys it.
There is some evidence behind the claims, but it's hard to uncover the detail.
The packaging says 'kills coronavirus on contact' and this is a claim repeated across the website. However, elsewhere it clarifies this is 'within one hour.'
Dr Ciric points out that 'there is no information on what the DiOX D4 coating is on the EVAQ site,' and it points you to another website, LiquidNano, but there is 'no specific information and no reference to any independent testing or publications giving evidence of efficacy' for the coating on that website either.
On another website, DiOXGlobal, the coating is described as a 'mechanical nano-scale coating that uses silica quaternary salts or QUATS'. Dr Ciric says there is some evidence of this having antiviral properties against enveloped viruses.
The EVAQ media release explains how Cambridge University scientists adjusted the international standard for antiviral textiles to include splash tests (to mimic coughing and sneezing), and used a mammalian coronavirus sample - to get as close to real world conditions as possible.
EVAQ prides itself on 'ergonomics' and notes that it has been designed by a 'specialist sportswear designer.'
We tried out the first version, but the design has now been tweaked.
This had an adjustable cord that fits behind the head, which is a nice idea because ear loops can be irritating, but there are two loops that go around the head and only a toggle on the top loop, so it takes a bit of fiddling with to get right.
It was also less easy to quickly slip on as you get on a train or pop into a shop, although it's easy to take off.
The top loop tended to slip down when we tried adjusting it, unless it was really tight and squashed down on the nose. The head straps can also bunch up your hair at the back.
It's breathable and fits quite snugly on the face, but there isn't a nose wire, so it could fog up your glasses if you wear them.
In their updated 'V2' design, EVAQ has added a nose wire and pleats to the front of the mask, which may help with the nose-squashing. The elastic head loops and top toggle look similar though, so there may still be issues with adjusting and hair-messing.
EVAQ says the mask can be washed 20 times at 40 degrees, but doesn't say how often you should wash it.
When we queried this, EVAQ told us it does not need to be washed after every use as the coating effectively 'self-sterilizes' and suggested a couple of times a week if wearing daily.
The manufacturer says this four-layer copper-infused face mask can destroy potentially harmful microbes immediately on impact.
It has a copper infused outer layer, a secondary filtration layer, a filter and lining for moisture absorption and ventilation, and a soft cotton layer against the face.
The Copper Clothing mask has recently been classified as an FFP2 mask, which means it meets requirements for medical masks that achieve more than 94% filtration.
Dr Ciric says 'copper is a known antimicrobial and has been used for this purpose for decades if not centuries.'
Copper Clothing makes no claims about the mask killing COVID-19, but says that its copper infused fabric has been tested against the bovine coronavirus - though there isn't a link to evidence for this.
When we asked the company about this, it sent us a snippet of the results of a test done in 2014 of the copper outer fabric, which confirmed its efficacy against bovine coronavirus within 10 minutes.
Copper Clothing claims that every strand of the outer layer of the mask is infused with copper, which is what some experts say is needed for the copper to have an effect.
The website does link to an independent lab certification showing the copper content of the face covering, as well as a link to certification of filtration efficiency.
We found the mask fitted well around the face, without gaps, and had a sturdy mouldable nose clip as well as adjustable ear loops.
The mask is a bit beak-like and there is a slight gap between your face and the inside of the mask, which quickly becomes a warm chamber of air and can be a bit uncomfortable.
But this does suggest that it is fitted closely to the face and trapping air well.
You can't wash this mask in the normal way: it needs to be soaked in distilled or cooled boiled water for at least five minutes and then gently massaged - it's a bit of a diva.
A cheap and simple pharmacy face covering which is infused with 'Silvadur antimicrobial technology.'
It says it is antibacterial (not antiviral) and the packaging is peppered with various logos of certification or branding - it's difficult to tell. It also mentions being antimicrobial, which is quite vague, so you could be forgiven for thinking it would kill COVID-19.
It's made from a polyamide/elastane blend.
Dr Ciric says: 'like copper, silver has known antimicrobial properties which have been well evidenced in the scientific literature. And, like copper, the exact way that it acts to kill microbes is not completely understood, but it likely binds to nucleic acids (DNA & RNA) and also interacts with fats and proteins.'
But, she notes, this mask doesn't offer any evidence of its antimicrobial effect. It uses Silvadur, a silver-based molecule produced by a company called DuPont.
On its website, DuPont provides evidence of Silvadur's antibacterial effect on two bacterial species but this isn't linked to an independent publication.
On the packaging, it says that Silvadur won't ever 'impact micro-flora, or good bacteria, when in contact with the skin.'
Dr Ciric says this is 'total drivel. The antimicrobial effect of silver is non-discriminatory. It may be more effective on some microbes than others but not on the basis of their u201cgoodnessu201d.'
The low price of this mask bears out in the quality when you put it on - it's large, loose and the ear straps aren't adjustable. There isn't a nose clip and it's only two layers.
It feels like wearing a cut out pair of tights on your face.
The face covering can be washed 40 times, according to the manufacturer.
A cotton mask infused with silver ions, which is meant to give it antibacterial properties. It's sold on Amazon.
This face covering uses Silvadur, the same technology as the Co-op mask above. It doesn't make any claims about COVID-19; the claims are that it's antibacterial.
Silver is a proven antimicrobial, but this mask doesn't offer any specific evidence around its efficacy in this context.
Surprisingly comfortable for a relatively cheap mask; it's breathable and the ear loops are adjustable, but there isn't a nose clip so air escapes a bit out the top.
The manufacturer says it can be washed 50 times without losing its antibacterial properties.
It says the maximum washing temperature is 100C, but also says to hand wash it - which you'd be brave (or stupid) to do at that level. Dr Ciric also says repeated washing at boiling point would likely remove the silver coating.
It doesn't say on the packaging, but the Amazon listing says it has three layers.
This relatively affordable mulberry silk face mask claims to be gentler on the skin, more breathable and to prevent 'maskne' (acne exacerbated by wearing a mask).
This mask doesn't make any specific antibacterial or antiviral claims, but does say that it will help reduce skin breakouts caused by mask wearing.
Silk is said to have antimicrobial properties, due to the natural presence of copper in the fibres that comes from the insects' diet. But we don't know exactly how that would work against COVID-19 and whether the levels of copper in silk would have enough of an effect.
It might be more to do with how hydrophobic silk is. Dr Ciric explains that 'a recent study (which has not yet been peer-reviewed) has shown that of the different fabrics tested, silk was the best at repelling water droplets. This means that any respiratory droplets carrying the virus may be repelled and will not absorb to the silk as well as to other fabrics.'
Dr Sweta Rai, a dermatologist, says it's true that silk is breathable, comfortable and less occlusive than many other common types of mask.
But, she notes that the more important thing in preventing skin breakouts is not what your mask is made of, but how long you have to wear it and how you care for your skin.
Watch our video on caring for your skin in between mask wearing below.
The mask is comfortable and breathable, though silk can be sweaty in warmer weather.
There is a nose clip but it isn't very comfortable and feels quite flimsy, and there are a few gaps around the face.
It's definitely the most stylish of the bunch, though.
Silk is hydrophobic, which means it repels moisture - a quality WHO guidelines state the outer layer of reusable face coverings should ideally have.
There's no limit on how much you can wash this mask, though the brand recommends hand washing or a cold wash, and line-drying it.
In the ever-growing market of 'germ-killing' face coverings, it can be hard to sift the facts from the marketing fluff. Here are three key things to check:
These terms are often used in a confusingly overlapping way. They sound promising, but you'll need to look for the specifics to see if they actually stand up to scrutiny.
Antimicrobial - this is a general umbrella term, meaning something that kills or inactivates microbes including viruses, bacteria, and fungus. Crucially, it doesn't mean it kills all of them. So it's to be taken with a pinch of salt.
Antibacterial - means acting against bacteria. This may help inhibit general bacterial growth if you're going longer between washes, but it's not going to be any use against COVID-19, which is a virus.
Antiviral - means something acts against viruses. But again, it's general, not specific, so doesn't necessarily cover you against all viruses. Look at the type of viruses the product has been tested against, and how. Remember that coronavirus is a family of viruses, not specifically COVID-19. They may act in similar ways, but it's still not a done deal.
This brings us to standards. The EVAQ mask and Virustatic Shield conform to a specific standard for antiviral textiles, which tells you that there has been some independent assessment of their efficacy at killing viruses.
Standards for reusable face coverings however are currently voluntary, and were somewhat rushed through as it's an emerging area. Don't take marketing terms at face value, and where possible, look for evidence of independent assessments or certification on product websites.
Face covering brands can make claims about the germ-kill properties of the fabric, but they can't claim the face covering protects you from COVID-19, and should have a disclaimer that they are not a medical device.
Some antimicrobial face coverings adhere to independent standards, like the Oeko-Tex Standard 100, which certifies that the material has been tested and deemed harmless to human health. You can look for the Oeko-Tex Standard 100 badge on product packaging.