Researchers prove UV light can kill flu viruses without harming humans

A new study appears to show that far-ultraviolet C (far-UVC) light can kill flu viruses and could reduce the incidence of flu infections.
Interesting Engineering

Far-ultraviolet C (far-UVC) light can kill flu viruses, and placing it in spaces like hospitals, airports, and schools could reduce the incidence of flu infections, according to a new study.

The far-UVC light does not damage human tissues. It has been known for a while now that broad-spectrum UVC light has the power to kill bacteria and viruses by breaking molecular bonds. This light is also used to sterilize surgical equipment. However, conventional germicidal lamps using broad-spectrum UVC light are unsafe for humans. They can cause skin cancer and cataracts in the eyes with prolonged exposure.

Far-UVC safe for humans

“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, director of the Center for Radiological Research at Columbia University Irving Medical Center.

However, this study did not use broad-spectrum UV light; it used far-UVC light, a narrow radiation spectrum. “This type of UV is also effective against illnesses and 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,” Brenner said in the study.

Until recently, conventional UV light was only efficient when people were not around. The Columbia team came up with a possible solution about five years ago. Light on the far end of the UV-C spectrum, known as far-UVC, has very short wavelengths. The researchers, led by Brenner, suspected it could penetrate and destroy microscopic bacteria and viruses. They discovered it cannot travel through the protective outer layers of human skin or eyes.

“We wanted to get all the benefits of UV light in terms of killing microbes, but none of the health hazards. We haven’t seen any biological damage to skin cells or eye cells, whereas with conventional UV light we’ve always seen lots of biological damage,” Brenner said.

Earlier studies have shown that exposure to far-UVC light does indeed appear to be safe. In their new study, Brenner and his colleagues released aerosolized particles of the H1N1 seasonal flu virus into a test chamber and exposed them to very low doses of far-UVC light. The light inactivated the viruses with the same efficiency as conventional germicidal UV light. A control group of bacteria not exposed to light remained active. Brenner and his colleagues have thus shown that UVC light can effectively kill airborne influenza.

Deadly flu bouts

This year has been accompanied by an especially deadly flu season in the US. It is forecast to be more toxic than the Swine Flu of 2009-2010, killing about 4,000 people a week. Researchers continue working to understand and explain the flu better and are working on more effective and accessible treatments. The study on far-UVC light, very low doses can inactivate flu viruses, but the results still need to be recreated and explored in various settings.

However, this finding can be a powerful tool if it is confirmed that this type of light can kill flu viruses without causing any human harm. This could mean that overhead lights could be placed in medical facilities, public spaces, and even homes to wipe out exposed viruses, stopping them from spreading and infecting new people.

You can read the study for yourself in the journal Nature.

Study abstract:

"Airborne-mediated microbial diseases such as influenza and tuberculosis represent major public health challenges. A direct approach to prevent airborne transmission is the inactivation of airborne pathogens, and the airborne antimicrobial potential of UVC ultraviolet light has long been established; however, its widespread use in public settings is limited because conventional UVC light sources are both carcinogenic and cataractogenic. By contrast, we have previously shown that far-UVC light (207–222 nm) efficiently inactivates bacteria without harm to exposed mammalian skin. This is because, due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (nonliving) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them. We show for the first time that far-UVC efficiently inactivates airborne aerosolized viruses, with a very low dose of 2 mJ/cm2 of 222-nm light inactivating >95% of aerosolized H1N1 influenza virus. Continuous very low dose-rate far-UVC light in indoor public locations is a promising, safe, and inexpensive tool to reduce the spread of airborne-mediated microbial diseases."

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