Scientists have trialled a rare form of ultraviolet light that can kill airborne germs and bacteria – such as influenza – and yet is harmless for humans.

The breakthrough is being hailed as a potential low-cost solution to eradicating viruses in trains, trams, airports, hospitals and offices.

The blight of workplace infection during flu season may be coming to an end. And so, too, the need to wear surgical masks when taking sneeze-laden public transport.

Scientists from the Centre for Radiological Research at Columbia University Irving Medical Centre claim the installation of low-cost overhead lamps beaming continuous low doses of what’s known as ‘far-UVC light’ in public spaces “could provide a powerful check on seasonal influenza epidemics, as well as influenza pandemics”.

The findings were published this week in Scientific Reports.

According to material provided on the university website, it’s been long known that broad-spectrum ultraviolet “is highly effective at killing bacteria and viruses by destroying the molecular bonds that hold their DNA together”.

In fact, this conventional UV light is routinely used to decontaminate surgical equipment.

“Unfortunately, conventional germicidal UV light is also a human health hazard and can lead to skin cancer and cataracts, which prevents its use in public spaces,” said study leader David J. Brenner, a Professor of Radiation Biophysics.

A germ-fighting robot in a US hospital uses ultra violet rays to eliminate germs in patients’ rooms. Photo: Getty

Several years ago, Dr Brenner and his team began experimenting with far-UVC – a narrow spectrum of ultraviolet light – as a tool to kill bacteria and viruses without damaging healthy tissue.

“Far-UVC light has a very limited range and cannot penetrate through the outer dead-cell layer of human skin or the tear layer in the eye, so it’s not a human health hazard,” said Dr Brenner.

“But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them.”

In earlier studies, Dr Brenner found that far-UVC light killed MRSA bacteria, a common cause of surgical wound infections, but without harming human or mouse skin.

In the latest study, aerosolized H1N1 virus – a common strain of flu virus – was released into a test chamber and exposed to very low doses of far-UVC light.

In effect, scientists were testing to see if far-UVC could kill the virus in the same sort of fine droplets that people produce by sneezing and coughing.

The far-UVC light was found to efficiently kill the flu viruses, with about the same efficiency as conventional germicidal UV light.

“If our results are confirmed in other settings, it follows that the use of overhead low-level far-UVC light in public locations would be a safe and efficient method for limiting the transmission and spread of airborne-mediated microbial diseases, such as influenza and tuberculosis,” said Dr Brenner.

He said the lamps currently cost less than $US1000 ($1270) each – and the costs would fall as the lamps were mass produced. This would amount to a cost-effective infrastructure spend for public transport companies, city councils and airports.

The positive impact on health costs would be in the many billions.