Wavelength‐dependent DNA Photodamage in a 3‐D human Skin Model over the Far‐UVC and Germicidal UVC Wavelength Ranges from 215 to 255 nm

, at UVC wavelengths from 215 to 255 nm (5 nm steps). At each wavelength, we measured yields of DNA-damaged keratinocytes, and their distribution within the layers of the epidermis. No increase in DNA damage was observed in the epidermis at wavelengths from 215 to 235 nm, but at higher wavelengths (240-255 nm) significant levels of DNA damage was observed. These results support use of far-UVC radiation to safely reduce the risk of airborne disease transmission in occupied locations.