Could a New Ultraviolet Technology Fight the Spread of Coronavirus?
A technique that zaps airborne viruses with a narrow-wavelength band of UV light shows promise for curtailing the person-to-person spread of COVID-19 in indoor public places.
The technology, developed by Columbia University’s Center for Radiological Research, uses lamps that emit continuous, low doses of a particular wavelength of ultraviolet light, known as far-UVC, which can kill viruses and bacteria without harming human skin, eyes and other tissues, as is the problem with conventional UV light.
“Far-UVC light has the potential to be a ‘game changer,’” said David Brenner, professor of radiation biophysics and director of the center. “It can be safely used in occupied public spaces, and it kills pathogens in the air before we can breathe them in.”
The research team's experiments have shown far-UVC effective in eradicating two types of airborne seasonal coronaviruses (the ones that cause coughs and colds). The researchers are now testing the light against the SARS-CoV-2 virus in collaboration with Thomas Briese and W. Ian Lipkin of the Center for Infection and Immunity in a biosafety laboratory on Columbia's medical center campus, with encouraging results, Brenner said.
The team previously found the method effective in inactivating the airborne H1N1 influenza virus, as well as drug-resistant bacteria. And multiple, long-term studies on animals and humans have confirmed that exposure to far-UVC does not cause damage to the skin or eyes.
"Our system is a low-cost, safe solution to eradicating airborne viruses minutes after they've been breathed, coughed or sneezed into the air."
If widely used in occupied public places, far-UVC technology has the potential to provide a powerful check on future epidemics and pandemics, Brenner said. He added that even when researchers develop a vaccine against the virus that causes COVID, it will not protect against the next novel virus.
“Our system is a low-cost, safe solution to eradicating airborne viruses minutes after they've been breathed, coughed or sneezed into the air,” Brenner said. “Not only does it have the potential to prevent the global spread of the virus that causes COVID-19, but also future novel viruses, as well as more familiar viruses like influenza and measles.”
Brenner envisions the use of safe overhead far-UVC lamps in a wide range of indoor public spaces. The technology, which can be easily retrofitted into existing light fixtures, he said, could be deployed in hospitals and doctors’ offices as well as schools, shelters, airports, airplanes and other transportation hubs.
Scientists have known for decades that germicidal UV light (wavelength around 254 nm) has the capacity to kill viruses and bacteria. Hospitals and laboratories often use germicidal UV light to sterilize unoccupied rooms, as well as other equipment. But conventional germicidal UV light cannot be used in the presence of people as it can causes health problems to the skin and eyes.
In contrast, far-UVC light, which has a very short wavelength (in the range from about 205 to 230 nm), cannot reach or damage living human cells. But these wavelengths can still penetrate and kill very small viruses and bacteria floating in the air or on surfaces.
Far-UVC lamps are now in production by several companies, although ramping up to large-scale production will take several months. At between $500 and $1000 per lamp, the lamps are relatively inexpensive, and once they are mass produced the prices would likely fall, Brenner said.
“Far-UVC takes a fundamentally different tactic in the war against COVID-19,” Brenner said. “Most approaches focus on fighting the virus once it has gotten into the body. Far-UVC is one of the very few approaches that has the potential to prevent the spread of viruses before they enter the body.”
FAR-UVC LIGHT: QUESTIONS AND ANSWERS
Ultraviolet (UV) light is a type of light that is similar to visible light but with different wavelengths, which makes it invisible to the human eye. UV light is usually divided into three categories, UVA, UVB and UVC, according to its wavelength.
UV light has been used for many years to disinfect locations such as hospital rooms and medical equipment. UV disinfection uses UVC light, which can kill microbes such as viruses and bacteria by damaging their genetic material, DNA or RNA.
Conventional germicidal UVC light usually has a wavelength of around 254 nanometers and is very efficient at killing viruses and bacteria. However, this type of UV light can penetrate into our eyes and into our skin, so if people are directly exposed to conventional germicidal UV light over long periods of time they may be at risk for eye damage and potentially skin damage. As a result, conventional UVC light can’t be used where people could be directly exposed to the UV light.
Far-UVC light has a shorter wavelength, usually around 222 nanometers. Far-UVC light also efficiently kills viruses and bacteria, but all available evidence shows that it is potentially safe for human exposure. This means that far-UVC lights, shining from above, can potentially be used to kill airborne viruses – including coronaviruses - in public places and when people are present.
Columbia scientists were the first to show that far-UV light efficiently kills human coronaviruses:
In more recent ongoing studies, Columbia scientists have clearly shown that far-UVC light efficiently kills the SARS-CoV-2 coronavirus that causes COVID-19. These ongoing studies have not yet been published.
Far-UVC light can penetrate only a very short distance in biological material. It can’t penetrate the layer of dead cells on the surface of our skin, nor the tear layer covering the surface of our eyes, so it can’t reach any living cells in the human body.
A number of different research groups, including at Columbia University, have performed extensive safety studies with far-UVC light and human skin, mouse skin, and mouse eyes, and all evidence suggesting that far-UVC light has no harmful effects. Examples are:
Columbia studies on far-UVC safety in human and mouse skin:
Japanese studies on far-UVC safety in mice:
UK study on far-UVC safety in human skin:
National and international safety regulations limit how much UV light can be used in public locations. These UV limits, established by the American Conference of Governmental Industrial Hygienists and the International Commission on Non-Ionizing Radiation Protection, have been in place for more than 20 years. Far-UVC lamps are required to conform with these existing safety regulations.
As the COVID-19 crisis slowly eases off, there will be many situations where people are moving closer together in indoor spaces: Hospitals, buses, planes, trains, train stations, schools, restaurants, offices, theaters, gyms - to name but a few. In all these situations it would be beneficial to have overhead far-UVC lights that are continuously killing microbes, including the COVID-19 virus – and so limiting the spread of the virus from one person to another.
Yes, in addition to COVID-19, far-UVC light is expected to be effective in reducing the spread of all viruses including influenza, measles, as well as the next potential pandemic virus.
There are several manufacturers of far-UVC lamps and their fixtures and they are rapidly building up their capacity. However, Columbia University cannot recommend particular brands or manufacturers.
All of these strategies help reduce the spread of COVID-19, but none are completely effective on their own. Together with all these existing techniques, far-UVC light has the potential to be a new and powerful tool to limit the spread of COVID-19 and other infectious diseases.