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Why We Aren’t Using UV to Disinfect Everything—Yet
Negative perception and costs pose obstacles to a promising technology
As the coronavirus pandemic continues, a technology that has existed for over 100 years is getting renewed attention as a promising disinfection tool. Ultraviolet germicidal radiation, which uses short-wavelength UV rays to kill bacteria and viruses, is already used to disinfect air, water, and surfaces in limited settings. In May, a report by the Illuminating Engineering Society, an authority on lighting technology, showed that UV-C germicidal radiation can play a key role in inactivating the SARS-CoV-2 virus, which causes Covid-19. Now some companies whose products use this technology are seeing heightened interest.
“The manufacturers can’t keep up with the demand right now,” says Edward A. Nardell, a professor of medicine at Harvard Medical School. “You’re going to see UV widely used as we continue with this pandemic and have no treatment.” This technology has previously been used in health care settings and is a standard method of potable water treatment, but it hasn’t been widely embraced because of negative public perception and concerns about costs.
The technology’s roots date to 1877, when scientists observed that sunlight could prevent the growth of bacteria inside a test tube. Shortwave UV rays kill or inactivate microbes by damaging their DNA, rendering them incapable of replicating. The discovery helped to stop the spread of measles in schools in the ’40s and the transmission of tuberculosis, says Nardell, but the demand dissipated as vaccines for these diseases were developed.
Germicidal UV is now sometimes perceived negatively, he says, because people confuse it with the UV-A and UV-B rays that cause sun-related damage. Germicidal UV technology uses a shorter wavelength of radiation, called UV-C, which is also generated by the sun but gets absorbed in the atmosphere, so it doesn’t pose as much of a risk to people outdoors. But even though UV-C rays are far less dangerous than UV-A and UV-B, overexposure to it indoors is still risky, and it’s still not safe for humans…
