'An underutilized tool:' UV-LED lights can kill coronaviruses and HIV
with the flip of a switch, study finds

Date:
March 29, 2022
Source:
University of Toronto
Summary:
The same light bulbs used in offices and public spaces can destroy
coronaviruses and HIV, according to a new study.



FULL STORY ==========================================================================
The same light bulbs used in offices and public spaces can destroy coronaviruses and HIV, according to a new study from U of T Scarborough.


========================================================================== Researchers killed both viruses using UV-LED lights, which can alternate between white light and decontaminating ultraviolet (UV) light. With
a cheap retrofit, they could also be used in many standard lighting
fixtures, giving them a "unique appeal" for public spaces, says Christina Guzzo, senior author of the study.

"We're at a critical time where we need to use every single possible
stop to get us out of this pandemic," says Guzzo, an assistant professor
in the department of biological sciences. "Every mitigation strategy
that can be easily implemented should be used." UV lights kill viruses
through radiation. Guzzo, alongside PhD students Arvin T. Persaud and
Jonathan Burnie, first tested the lights on bacterial spores notorious
for their resistance to this radiation (known as Bacillus pumilus spores).

"If you're able to kill these spores, then you can reasonably say
you should be able to kill most other viruses that you would commonly
encounter in the environment," says Guzzo, principal investigator at
the Guzzo Lab.

Within 20 seconds of UV exposure, the spores' growth dropped by 99
per cent.



==========================================================================
The researchers then created droplets containing coronaviruses or HIV,
to mimic typical ways people encounter viruses in public, such as from coughing, sneezing and bleeding. The droplets were then exposed to
UV light and placed in a culture to see if any of the virus remained
active. With just 30 seconds of exposure, the virus' ability to infect
dropped by 93 per cent.

Upon testing the viruses at different concentrations, they found samples
with more viral particles were more resistant to the UV lights. But
even with a viral load so high Guzzo calls it "the worst-case scenario," infectivity dropped 88 per cent.

Though it wasn't included in the study, Guzzo and her students
also compared UV light to two heavy duty disinfectants used in lab
research. They found the lights were similarly effective in their ability
to deactivate viruses.

"I was really surprised that UV could perform on the same level of those commonly used lab chemicals, which we regard as the gold standard,"
she says.

"That made me think, 'Oh, my gosh, this is a legitimate tool that's
really underutilized.'" Balance UV's pros and cons with clever use, researchers say While the lights still left a small percentage of the
virus viable, Guzzo references the "Swiss cheese model" of defence
against COVID. Every strategy to fight the spread has its holes, but
every layer is another chance to stop straggling virus particles.



========================================================================== Repeated exposure to UV light is key to catching those missed particles -
- fortunately, it's as easy as flipping a switch. It's also simpler to
change a light bulb than an air filtration system. Guzzo notes that
UV-LEDs are cheap and could be easy to retrofit in existing light
fixtures, and that the bulbs are long-lasting and simple to maintain.

"You could disinfect in a way that wouldn't be infringing on people's
enjoyment of that everyday 'normal' life that they long for," Guzzo says.

The lights also benefit from automation. A standardized, germicidal dose
of light can be delivered each time, while the process of wiping down
spaces with disinfectants leaves room for human error. Chemicals and
waste from these disinfectants also end up in watersheds and landfills
as hands are washed and wipes thrown away.

But the lights aren't harmless, and there's a reason for wearing
sunscreen and sunglasses -- UV radiation damages nucleic acid, and
repeated, prolonged exposure is harmful. That's why Guzzo says the
lights should be used when public spaces are empty, such as vacated
buses that have finished their routes, or empty elevators travelling
between floors. Escalator handrails could be continuously disinfected
by putting UV lights in the underground part of the track, cleaning it
with each rotation.

Safe Antivirus Technologies, Inc., a Toronto-based start-up company that partnered with Guzzo for the study, is developing unique UV-LED lighting modules. With motion sensors, the lights automatically switch to UV
light when a room is empty, then turn back to regular light with movement.

Funded by the Natural Sciences and Engineering Research Council (NSERC) Alliance COVID-19 Grant and published in theVirology Journal, this study highlights UV-LEDs as a tool that could be used beyond the pandemic,
ideally to help prevent another.

"Worldwide events like the COVID-19 pandemic, as terrible as they
are, hopefully can still be learned from," Guzzo says. "One thing we
learned is that this is an underutilized tool we should think more
about implementing."

========================================================================== Story Source: Materials provided by University_of_Toronto. Original
written by Alexa Battler.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Arvin T. Persaud, Jonathan Burnie, Laxshaginee Thaya, Liann DSouza,
Steven Martin, Christina Guzzo. A UV-LED module that is highly
effective at inactivating human coronaviruses and HIV-1. Virology
Journal, 2022; 19 (1) DOI: 10.1186/s12985-022-01754-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220329152831.htm

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