Question: You talked about sunlight in a previous post, but I was just reading about a special type of ultraviolet light — Far-UVC rays (check out this Columbia University article), which seems promising. What do you think?
Answer: Super interesting! We talked about sunlight and Vitamin D in our Q&A of 4/24, but we didn’t delve into ultraviolet light. Most ultraviolet light damages our cells and does so exceptionally quickly. The BBC article I referenced on 4/24 does an excellent job laying out the issues, including describing the potential benefits of Far-UVC. In short, Far-UVC does seem promising, especially for preventing antibiotic-resistant infections! But, the science is still very limited with only lab-based petri-dish and animal studies having been conducted. More research would be needed — research that includes human subjects — before we would start using widely using Far-UVC. Here’s a bit more information on what we currently know about Far-UVC:
- It is less dangerous to handle than other forms of UVC but still lethal to viruses and bacteria
- Per this Nature article, “due to its strong absorbance in biological materials, far-UVC light cannot penetrate even the outer (non living) layers of human skin or eye; however, because bacteria and viruses are of micrometer or smaller dimensions, far-UVC can penetrate and inactivate them.”
- Does not damage human skin cells based on culture dish (in vitro) study (note: the same study exposed hairless mice to Far-UVC and also noted that it did not damage mice skin cells); and
- Has been shown to prevent mouse wounds from becoming infected with the drug-resistant bacteria and also been shown to kill areosolized H1N1 influenza virus.
Finally, a pre-print study (not yet peer-reviewed) was just released last week, which studied Far-UVC effects on two aerosolized (e.g. airborne) coronaviruses (not SARS-CoV-2). The authors concluded that “very low doses of far-UVC light efficiently kill airborne human coronaviruses carried by aerosols.” The authors further recommended exploring the use of Far-UCV light for disinfecting indoor public spaces, not just for COVID-19, but for other types of viruses and bacteria. This is an exciting area of innovation! I look forward to more human studies to ensure safety before we delve into widespread use.