Continuous low doses of far ultraviolet C (far-UVC) light can kill airborne flu viruses without harming human tissues, a new study reveals
Findings from research carried out at the Center for Radiological Research, Columbia University Irving Medical Center (CUIMC) suggest that use of overhead far-UVC light in public spaces could provide a powerful check on seasonal influenza epidemics, as well as influenza pandemics.
Broad-spectrum UV light, which has a wavelength of between 200-400 nm, is highly effective at killing bacteria and viruses by destroying the molecular bonds that hold their DNA together. This conventional UV light is routinely used to decontaminate surgical equipment. This light, however, poses a risk to human health.
“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,” explained study leader Dr David J. Brenner, the Higgins Professor of Radiation Biophysics at the Vagelos College of Physicians and Surgeons and Director of CUIMC. He also serves as Professor of environmental health sciences at Columbia’s Mailman School of Public Health.
Brenner and his colleagues had hypothesised that a narrow spectrum of UV light, called far-UVC, could kill microbes without damaging healthy tissue.
In their earlier studies, Brenner’s team demonstrated that far-UVC light generated by filtered excimer lamps emitting in the 207–222 nm wavelength range, was effective at killing MRSA (methicillin-resistant S. aureus) bacteria, a common cause of surgical wound infections but not harm human or mouse skin.
“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. But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them,” explained Brenner, who also serves as Professor of environmental health sciences at Columbia’s Mailman School of Public Health.
Influenza virus spreads from person to person mainly through fine liquid droplets, or aerosols, that become airborne when people with flu cough, sneeze, or talk.
The new study was designed to test if far-UVC light could efficiently kill aerosolised influenza virus in the air, in a setting similar to a public space. Scientists hope the new technology could be used in hospitals, doctors’ offices, schools, airports, aeroplanes to stop the spread of the influenza virus.
In the study, aerosolised H1N1 virus – a common strain of flu virus – was released into a test chamber and exposed to very low doses of 222 nm far-UVC light. A control group of an aerosolised virus was not exposed to the UVC light. The far-UVC light efficiently inactivated 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 Brenner.
“And unlike flu vaccines, far-UVC is likely to be effective against all airborne microbes, even newly emerging strains,” Brenner concluded.
The study, titled “Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases” features contributions by David Welch, Manuela Buonanno, Veljko Grilj, Igor Shuryak, Connor Crickmore, Alan Bigelow, Gerhard Randers-Pehrson, and Gary Johnson (all at CUIMC).