Low intensity UV kills SARS-CoV-2 after a while
“It has already been shown that a high intensity of UV-C LED radiation can inactivate the SARS-CoV-2 virus rapidly,” according to the company. “In realistic applications, like upper air treatment or secondary air treatment devices [photos], the necessary dose to eliminate the virus is applied over several cycles.”
By this it means that virus-containing air will have to pass by a low-intensity UV-C source several times before almost all the virus is inactivated.
The dose for inactivating the SARS-CoV-2 virus was evaluated, as well as its consistency over a #100:1 span of radiation levels.
“For the experiment, a fixture was equipped with 275nm Oslon UV 3636 in 4mW and 42mW power classes, and placed at 300mm to the pathogens,” said Osram. “Uniform irradiance of the probe was realised by a light mixing chamber and the irradiance determined under the consideration of all reflections.
The research results express the amount of virus inactivated in ‘log reduction’:
log10(number before/number after).
“At low intensity levels a dose of 2,7mJ/cm2 for a log3 reduction [up to 99.9% inactivated] and 3,6mJ/cm2 for log4 [up to 99,99%] have been derived.”
The company added that inactivation is independent of Covid-19 virus variant.
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(Caveat: the last column was calculated at Electronics Weekly. Osram has been asked to check it)
Oslon UV 3636
Images above are artist’s impressions of possible future deployment supplied by Osram and not current anti-viral UV-C medical equipment.