Continuous low doses of far ultraviolet C (far-UVC) light could be a possible way to kill off influenza viruses while they are still airborne, according to a new study. All this could happen without any negative effects on humans since it can’t penetrate our skin.

The research was conducted at the Center for Radiological Research at Columbia University Irving Medical Center (CUIMC) and the study is published in Scientific Reports. It builds on the well-established idea of using ultraviolet light to sterilize instruments and surfaces. Currently, the wavelength used also harms us, as it can lead to skin cancer and cataracts.

"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," senior author Dr David J. Brenner from CUIMC, said in a statement. "But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them."

Far-UVC has previously been demonstrated to be effective in killing off bacteria like the dangerous methicillin-resistant Staphylococcus aureus, a superbug that has developed a resistance to antibiotics. The bacterium is a common cause of infections in hospitals, and using far-UVC could be a way to fight it off without it developing more immunity to antibiotics.

Many diseases can travel on small droplets caused by people coughing and sneezing, so it is better to catch the viruses when they are in flight. The researchers designed a test in which a common strain of the flu H1N1 was aerosolized and exposed to low levels of far-UVC at a wavelength of 222 nanometers. The light was as effective against the viruses as traditional 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," Dr Brenner added. "And unlike flu vaccines, far-UVC is likely to be effective against all airborne microbes, even newly emerging strains."

UVC lamps currently costs $1,000, but if the cost can be reduced and follow-up studies confirm the findings, they could become an important way to reduce flu epidemics.