Your First Line of Defense Against Viral Infections and Other Pathogens
Invisible ultraviolet light in the far-UVC wavelength range is a first line of defense that can deactivate airborne viruses before you breathe them in. A second line of defense—your face mask—doesn't deactivate viruses but can stop them from entering your body. Vaccines then act as a third line of defense by preventing viruses from replicating after they've already entered your body and infected you. All three lines of defense will be important as Covid-19 becomes an endemic disease. But wide deployment of UVC disinfection at the front lines can dramatically lessen the viral load in the air, increasing the effectiveness of the second and third lines of defense.
The Far-UVC Safety
Far-UVC light, at wavelengths from 200-to-240 nanometers, deactivates viruses in the air but doesn't penetrate the skin far enough to reach live cells. When it reaches your body, your external"stratum corneum" layer of dead skin cells absorbs the light before it reaches your living cells. And when it reaches your eye, your protective tear layer absorbs the short far-UVC light waves before they can reach your cornea. Therefore far-UVC light can be used in many locations where longer-wavelength 254nm UVC light cannot be used.
How UVC Light Deactivates Viruses
UVC light neutralizes viruses, bacteria, and other pathogens on surfaces and in air by disrupting their nuclear RNA to prevent them from reproducing. For more than a hundred years, UVC light has been used to sanitize air, surfaces, and water in factories, water treatment plants, office-buildings, schools, public transportation, and many other public and private spaces. Unfortunately, traditional UVC light at 254 nanometers can harm skin and eyes, so it has to be turned off when people are around. But recent academic research has found that shorter-wavelength UVC light known as "far-UVC" light, is less harmful to skin and eyes and can be used in many more places where people congregate.
New Applications for a
The traditional 254 nm UVC light that has been used for disinfection for more than 100 years suffers from a major drawback: it can't be used around people because its longer wavelength penetrates and damages live cells in skin and eyes. To avoid human harm, it has to be used when no one else is in a room. Or, it must be enclosed in HVAC systems or installed high in the room and pointed at the ceiling. Therefore its applications are limited, especially in situations where people are actively spreading the virus in airspace that's not being constantly disinfected. But because short-wavelength far-UVC light can be used more safely around people, it can directly disinfect the air and surfaces in locations where people gather. It enables an entirely new approach to UVC disinfection, providing constant, proactive disinfection, rather than reactive, after-the-fact treatment of air and surfaces. We can expect to see far-UVC light deployed everywhere—in restaurants, schools, at work, in stores, in homes, and anywhere else people need to be protected from viruses and other pathogens.