Introduction of Far UVC

What is Far UVC?

Far UVC is an ultraviolet light with a wavelength range of 207 – 222 nm.

Far UVC can kill germs, such as viruses and bacteria, without being harmful to humans.

Is it true that far-UVC light can be used against coronavirus without harming people?

There is only a narrow band of frequency, basically represented as a single wavelength, 207 nm, that is capable of penetrating the cells of bacteria but not capable of penetrating human cells due to their significantly larger size. Presumably it is equally good at disrupting viruses.

What blocks UVC light?

Glass, any piece of metal, paint, almost anything you cannot see through will also block UV, as will many things that you can see through. A UVC lamp must be made of quartz to pass the UVC light, regular window glass will block uv light. But need to be noticed that a lot of transparent plastics will block UV light, including UV-C, with just a relatively thin film. Polycarbonate, which is a very strong plastic, absorbs strongly in this region and is used for safety glasses. Even so, do not expect these glasses to protect again strong UV sources such as UV-range laser beams especially directed at the eye. Glass, in general, unless specifically coated with other materials, offers virtually no protection. The value of the complex part of the index of refraction, called the extinction coefficient, k, is far too low in the UVC range.

Does far uvc kill coronavirus?

Far-UVC is presented as a promising candidate against COVID-19 since it can inactivate pathogens including viruses and bacteria without harming mammalian skin or eyes. Furthermore, the work also points out the applicability of far-UVC lights for public spaces and treatment of selective region in COVID-19 patients by using fiberoptic as the medium for high-risk cases where chances of survival are low and such treatment may avoid fatality due to the COVID-19.

Also, as scientific reports show, a direct approach to limit airborne viral transmissions is to inactivate them within a short time of their production. Germicidal ultraviolet light, typically at 254 nm, is effective in this context but, used directly, can be a health hazard to skin and eyes. By contrast, far-UVC light (207–222 nm) efficiently kills pathogens potentially without harm to exposed human tissues. We previously demonstrated that 222-nm far-UVC light efficiently kills airborne influenza virus and we extend those studies to explore far-UVC efficacy against airborne human coronaviruses alpha HCoV-229E and beta HCoV-OC43. Low doses of 1.7 and 1.2 mJ/cm2 inactivated 99.9% of aerosolized coronavirus 229E and OC43, respectively. As all human coronaviruses have similar genomic sizes, far-UVC light would be expected to show similar inactivation efficiency against other human coronaviruses including SARS-CoV-2. Based on the beta-HCoV-OC43 results, continuous far-UVC exposure in occupied public locations at the current regulatory exposure limit (~3 mJ/cm2/hour) would result in ~90% viral inactivation in ~8 minutes, 95% in ~11 minutes, 99% in ~16 minutes and 99.9% inactivation in ~25 minutes. Thus while staying within current regulatory dose limits, low-dose-rate far-UVC exposure can potentially safely provide a major reduction in the ambient level of airborne coronaviruses in occupied public locations.