In a landmark study, researchers found that UV light-emitting diodes (LEDs) can quickly and effectively kill the human coronavirus. If they are effective against SARS-CoV-2, this technology could be an inexpensive way to disinfect surfaces, ventilation systems, and water systems.
It is well known that SARS-CoV-2, which is the virus that causes COVID-19, can spread through respiratory droplets and surfaces contaminated by nasal, mouth, and eye secretions.
According to a review article in the journal Environmental Research, SARS-CoV-2 was present in air samples from areas such as hospital rooms and elevators. It was also measurable in poorly ventilated or crowded spaces.
SARS-CoV-2 was also viable for several days on common surfaces, such as stainless steel and plastic.
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Because of the urgent need to find effective disinfection methods for SARS-CoV-2, researchers from Tel Aviv University in Israel — in collaboration with the University of Haifa, Oranim Academic College, and Chaim Sheba Medical Center at Tel HaShomer — set out to investigate whether or not irradiation using UV LED would inactivate human coronaviruses.
They recently published their results in the Journal of Photochemistry and Photobiology B: Biology.
Scientists put UV LEDs to the test
Using the human coronavirus OC43 (HCoV-OC43) as a substitute for SARS-CoV-2, the research team tested different UV LED bulbs emitting varying wavelengths — measured in nanometers (nm) — to see which would effectively inactivate the HCoV-OC43 virus.
After exposing viral suspensions placed in darkened tubes to UV LED light, the team found that wavelengths of 285 nm were highly effective at inactivating the virus and almost as effective as wavelengths of 265 nm, inactivating 99.9% of the coronavirus in under 30 seconds.
Furthermore, other viruses showed similar sensitivity to these wavelengths, indicating that this technology could be useful against many types of human coronavirus, including SARS-CoV-2.
The researchers say that these findings are significant because not only does the 285-nm UV LED light disinfect coronaviruses, but it is also less expensive and more readily available than the 265-nm variety.
“We discovered that it is quite simple to kill the coronavirus using LED bulbs that radiate [UV] light.”
— Prof. Hadas Mamane
Because the researchers used HCoV-OC43 instead of SARS-CoV-2, they say that their future work will aim to confirm these results by testing the impact of LEDs and their combinations on the virus that causes COVID-19.
Why did they use a surrogate virus?
As study co-author Dr. Yoram Gerchman told Medical News Today, “SARS-CoV-2 requires a Bio Safety Level 3 (BSL3) laboratory to propagate (although not for analysis) because the disease it causes is much more severe.”
“The [HCoV-OC43 virus] needs only a Bio Safety Level 2 [laboratory]. At the time, the BSL3 [laboratory] in [the] Sheba hospital virology center was under renovation, and we did not want to delay.”
Dr. Gerchman explains that it is common to use bacteriophages, which are viruses that infect bacteria but not humans, as surrogates, as researchers can work with them in a Bio Safety Level 1 laboratory.
Additionally, the surrogate virus the team used in the study belongs to the same betacoronavirus genus as SARS-CoV-2 and closely resembles it in size and structure.
Despite the success of UV LED irradiation on human coronaviruses, the Tel Aviv University press release warns that this technology is hazardous and does not recommend it for residential use. The authors say that designing a system to utilize UV LEDs while preventing its harmful effects is necessary.
Could UV LED disinfection be safer?
The COVID-19 pandemic has increased the use of disinfectants in both public settings and households.
Recent research in the journal Environmental Science & Technology Letters found an increase in the number of quaternary ammonium compounds (QACs) in house dust collected from homes after the pandemic began. QACs are chemicals in cleaning and disinfecting products that cause reproductive and respiratory harm.
Additionally, the use of large amounts of disinfectant chemicals can harm wildlife and urban environments, according to a review in the journal Environmental Research.
Due to the hazards of chemical methods, professionally designed UV LED disinfection systems may be a safer solution — one that can disinfect surfaces, air, and water.
According to Prof. Mamane, the researchers “killed the viruses using cheaper and more readily available LED bulbs, which consume little energy and do not contain mercury like regular bulbs.”
“Our research has commercial and societal implications, given the possibility of using such LED bulbs in all areas of our lives, safely and quickly.”
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