Banner image: The ultraviolet light from a krypton chloride excimer lamp is powered by molecules moving between different energy states. (Source: Linden Research Group)
New research from the University of Colorado Boulder has found that certain wavelengths of ultraviolet (UV) light are not only extremely effective at killing the virus that causes COVID-19, but they are also safer to use in public places.
The study, published this month in the journal Applied and Environmental Microbiology, is the first comprehensive analysis of the effects of different wavelengths of ultraviolet light on SARS-CoV-2 and other respiratory viruses, including the only one that is safer for the organisms and does not require contact wavelengths. Protect.
The authors call these findings a “game changer” for the use of UV light that could lead to new affordable, safe and effective systems for reducing the spread of viruses in crowded public spaces such as airports and concert venues.
“Of almost all the pathogens we have studied, this virus is by far one of the easiest to kill with ultraviolet light,” said senior author Carl Linden, professor of environmental engineering. “It requires very low doses. This shows that UV technology can be a very good solution for protecting public spaces.”
Ultraviolet rays are naturally emitted by the sun, and most forms are harmful to living things as well as microorganisms such as viruses. This light can be absorbed by an organism’s genome, tying knots in it and preventing it from reproducing. However, these harmful wavelengths from the Sun are filtered out by the ozone layer before they reach the Earth’s surface.
Some common products, such as fluorescent lamps, use ergonomic UV rays, but have an internal coating of white phosphorus that protects them from UV rays.
“When we remove the coating, we can emit wavelengths that can be harmful to our skin and eyes, but they can also kill pathogens,” Linden said.
Hospitals are already using UV technology to disinfect surfaces in unoccupied areas and using robots to use UV light between operating rooms and patient rooms.
Many gadgets on the market today can use UV light to clean everything from cell phones to water bottles. But the FDA and EPA are still developing safety protocols. Linden cautions against using any personal or “sterilizing” equipment that exposes people to ultraviolet light.
He said the new findings are unique because they represent a middle ground between ultraviolet light, which is relatively safe for humans and harmful to viruses, especially the virus that causes COVID-19.
In this study, Linden and his team compared different wavelengths of UV light using standardized methods developed throughout the UV industry.
“We think let’s come together and make clear statements about the amount of UV exposure needed to kill SARS-CoV-2,” Linden said. “We want to make sure that if you use UV light to fight the disease, you will be successful “. Dosage to protect human health and human skin and kill these pathogens.”
Opportunities to perform such work are rare as working with SARS-CoV-2 requires extremely stringent safety standards. So Linden and Ben Ma, a postdoctoral fellow in Linden’s group, teamed up with virologist Charles Gerba of the University of Arizona in a laboratory licensed to study the virus and its variants.
The researchers found that while viruses are generally very sensitive to ultraviolet light, a certain far-ultraviolet wavelength (222 nanometers) is particularly effective. This wavelength is created by krypton chloride excimer lamps, which are powered by molecules that move between different energy states and are very high energy. As such, it is capable of causing more damage to viral proteins and nucleic acids than other UV-C devices and is blocked by the outer layers of a person’s skin and eyes, meaning it does not have any harmful health effects. kills the virus.
UV rays of varying lengths (measured here in nanometers) can penetrate different layers of the skin. The deeper these wavelengths penetrate the skin, the more damage they cause. (Image source: “Far UV: Current State of Knowledge” published by the International Ultraviolet Radiation Association in 2021)
Since the early 20th century, various forms of UV radiation have been widely used to disinfect water, air, and surfaces. As early as the 1940s, it was used to reduce the spread of tuberculosis in hospitals and classrooms by lighting the ceiling to disinfect the air circulating in the room. Today it is used not only in hospitals, but also in some public toilets and on airplanes when no one is around.
In a white paper recently published by the International Ultraviolet Society, Far-UV Radiation: Current State of Knowledge (along with new research), Linden and co-authors argue that this safer far-UV wavelength can be used along with improved ventilation, wearing masks and vaccination are key measures to mitigate the effects of current and future pandemics.
Linden Imagine systems can be turned on and off in closed spaces to regularly clean air and surfaces, or create permanent invisible barriers between faculty and students, visitors and maintenance staff, and people in spaces where social distancing cannot be maintained.
UV disinfection can even rival the positive effects of improved indoor ventilation, as it can provide the same protection as increasing the number of air changes per hour in a room. Installing UV lamps is also much less expensive than upgrading your entire HVAC system.
“There is an opportunity here to save money and energy while protecting public health. It’s really interesting,” Linden said.
Other authors on this publication include: Ben Ma, University of Colorado, Boulder; Patricia Gandy and Charles Gerba, University of Arizona; and Mark Sobsey, University of North Carolina, Chapel Hill).
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Post time: Nov-03-2023