Of all the regions of the electromagnetic spectrum, none have had the same level of coronavirus controversy as ultraviolet (UV).

Earlier this year, social media sites were rife with rumours about the covid-killing qualities of UV light – or sunlight, which contains three types of UV. One post, falsely attributed to UNICEF, extolled the benefits of sunbathing while warning against ice cream consumption.

Then, in April, President Trump mentioned a “very nice rumour” according to which sunlight has “an effect” on viruses. He then suggested “we hit the body with a tremendous […] ultraviolet or just very powerful light.”

Ultraviolet coronavirus therapy debunked

Such claims have been widely debunked by scientists and industry experts. In fairness, UV light can destroy viruses – it’s just that it’s equally harmful to the human body. “You would be literally frying people,” laughed Dan Arnold, a marketing manager at UV Light Technology.

But used safely, UV light can be a weapon of mass disinfection. Robots in China now use ultraviolet light to disinfect hospital waiting rooms and operating theatres. Public transport, from New York to Shanghai, is routinely fitted with UV lamps to kill harmful microbes.

Swoxid mask
All rights Swoxid.

The latest addition to this list comes from scientists at Swiss-based start-up Swoxid. They’ve created a mask which uses UV light to destroy airborne pathogens – including the novel coronavirus.

Behind the Swoxid mask

A breakdown of the mask prototype was published in this month’s Advanced Functional Materials.

In terms of appearance, it’s not too dissimilar to a regular cotton mask. The only difference is the plastic grid clamped on to the front, attached to what appears to be filter paper.

But as lead author Endre Horváth points out, the filter is actually ceramic – formed by fusing together titanium dioxide nanowires. Its pores, each 100 nanometres wide, are small enough to trap the coronavirus germ (which measures around 120 nanometres).

When illuminated by UV light, the mask fibres convert resident moisture (such as saliva) into reactive oxygen species like hydrogen peroxide. These unstable molecules damage all organic species they come into contact with, including viruses.

“In terms of disinfection, the user does not need to do anything else than putting and closing it in the portable UV-box, push a button and launch the UV cleaning cycle,” says Horváth.

László Forró – who also worked on the project – likens this UV-box to a Ray-Ban sunglasses case. Then he reconsiders.

“Maybe it is better to use the analogy to Dolce & Gabbana, because it has a hard case, contrary to Ray-Ban, with its soft case,” he clarifies.

Forro Horvath
Photo credit: Zeno Karl Schindler Foundation

Testing and investing

So, is the Swoxid mask set to become a familiar sight?

Possibly – but further trials await the prototype before it’s seen outside the pages of Advanced Functional Materials. The filter is proven to destroy E. coli bacteria and rupture DNA strands within minutes, but hasn’t been tested on coronavirus.

“Conceptually, viruses are not different, they are also built from organic molecules,” explains Forró. He says the mask will be shown to “efficiently destroy” viruses before it’s made commercially available.

In turn, that commercialisation depends on the levels of investment and interest that Swoxid can generate.

If funds are forthcoming, the researchers believe their mask can address the Personal Protective Equipment (PPE) shortages which still afflict hospitals. A report this month showed that only 40% of UK doctors believe they have adequate supplies of of FFP3s – masks which need to be thrown away after a single use to avoid infection.

The Swoxid scientists estimate their mask could be used up to a thousand times each. And they believe there’s “no upper limit” for the number that could be manufactured on an industrial production line.

Far Away Places

The team also hopes their mask can solve the environmental issues caused by millions of masks being discarded everyday. One study calculates that if the UK population each used one mask a day for a year, it would result in 66,000 tonnes of waste. Some fear there will be more masks in the Mediterranean than jellyfish.

And according to Forró, the filter has another use: it can be used for solar-powered water disinfection. “It has great potential in remote places, underdeveloped countries, where access to drinkable water is difficult,” he says.

It’s a sobering reminder. While covid-19 occupies our attention and dominates the news cycle, other crises – unseen, unheard – are unfolding.

But it’s some comfort to know that, though FFP3s may end up haunting stretches of the Mediterranean, the technology developed by Horváth and his team might be purifying water and saving lives.

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