Even as conventional UV-C lamps fight Covid, LED version is becoming a reality.
LEDsmagazine.com Jun 23rd, 2020 . ( re-edited for crispness by ledchip team)
On the heels of Signify announcing it is cranking up production of ultraviolet-C-band (UV-C) lamps proven to kill the coronavirus in a lab, Osram said that it, too is ramping up output of conventional mercury discharge products. Osram did not rule out eventually using LED technology for UV-C.
Signify provided to a Boston University lab, where a research team showed that the UV radiation (5 mJ/cm2-6 Seconds) killed 99% of SARS-CoV-2, commonly known as the coronavirus, which causes COVID-19. The Boston team said that a larger dose (22mJ/cm2- 25 seconds) than what it used could deactivate over 99.999% of the virus. The Boston university’s National Emerging Infectious Diseases Laboratories (NEIDL) exposed materials containing the virus to a UV-C tube lamp from Signify. It found that a dose of 5 mJ/cm2 resulted in “a reduction of the SARS-CoV-2 virus of 99% in 6 seconds.” (SARS-CoV-2 is the more scientific name for the novel coronavirus).
The NEIDL team extrapolated that a stronger dose of 22 mJ/cm2 would result in a reduction of 99.9999% in 25 seconds.
“Our test results show that above a specific dose of UV-C radiation, viruses were completely inactivated: In a matter of seconds we could no longer detect any virus,” said team leader Anthony Griffiths, associate professor of microbiology at Boston University. “We’re very excited about these findings and hope that this will accelerate the development of products that can help limit the spread of COVID-19.”
Guangdong Detection Center of Microbiology determined that an AirZing model 5040 lamp provided by Osram China Lighting Ltd. killed 99.8% and 99.9% of a similar virus, H3N2, in a series of six “air virus elimination tests” that started in March and concluded on May 6. Coronavirus samples were not available at the time of testing.
International Ultraviolet Association (IUVA) states that UVC Radiation as between 200 and 280 nm “inactivates at least two other coronaviruses that are near-relatives of the COVID-19 virus: 1) SARS-CoV-1and 2) MERS-CoV.”
The effectiveness of UV light in practice depends on factors such the exposure time and the ability of the UV light to reach the viruses in water, air, and in the folds and crevices of materials and surfaces. There are questions whether the light can effectively penetrate a droplet that might carry the virus in aerosol form.
UV-C lighting has been used extensively for more than 40 years in disinfecting drinking water, waste water, air, pharmaceutical products, and surfaces against a whole suite of human pathogens, the IUVA noted.
UV-C is dangerous to human skin and eyes, so Osram outfits the AirZing with sensors that turn off the light when a person enters a room. UV-C light should only be used by trained staff.
Germicidal UV-C was the subject of an informative talk by Bob Karlicek, director of the Center for Lighting Enabled Systems & Applications (LESA) at Rensselaer Polytechnic Institute, in a recent LEDs Magazine webinar.
The “far UV-C”, an even shorter-wavelength UV, can be a safer light than UV-C while still killing viruses, and are examining it in particular at 222 nm. Its technology includes discharge sources as well as lasers. LESA’s Karlicek maintained that it won’t be suitable for LEDs (!)
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