Author: Isabel Zhang
From: Chicago, IL, US
Image Credit: Gettyimages
You’ve probably heard of ultraviolet (UV) light— after all, it’s what radiates from the sun and makes you tan or (painfully) sunburnt.
However, you may not have heard of the good side of UV light— like how it’s used to kill microbes including bacteria and viruses. And there's a particularly relevant virus today that it can kill: SARS-CoV-2, the virus that causes COVID-19.
The Three Types of UV Light
First, let’s explore the three different types of UV light:
UVA- Has the least energy. What you’re mainly exposed to when you’re out in the sun.
UVB- Sits in the middle of the light spectrum. Present in a small portion of sunlight.
UVC - Has the most energy. We’re not normally exposed on a daily basis because most of it is absorbed in the Earth’s ozone; however, there are human-made sources of UV light.
UVC light is the type that’s most effective at killing germs and what we’ll be focusing on.
Past/Current Use of UVC Light
UVC radiation is a known disinfectant for surfaces, air, and liquids. It kills germs by damaging molecules like nucleic acids and proteins, inhibiting biological processes the germ needs for survival.
UVC radiation has been used for decades. Consumers purchase UVC lamps known as “germicidal lamps” to disinfect surfaces in their home. Hospitals and laboratories often use germicidal UV light to sterilize unoccupied rooms, as well as other equipment.
What We Know About UVC Light and COVID-19
UVC light has previously been shown to destroy the outer protein coating of the SARS-Coronavirus (a different coronavirus strain that resulted in an epidemic from 2002-2004), leading to inactivation of the virus.
In more recent studies, scientists at Columbia University have clearly shown that far-UVC light (a type of UVC light) efficiently kills the SARS-CoV-2 coronavirus causing COVID-19. In addition, a number of different research groups have performed extensive safety studies on UVC light with human skin, mouse skin, and mouse eyes. The results of these studies suggest that UVC light has no harmful effects.
Approaching UVC Light With Caution
Before we’re ready to blast homes and public spaces with UVC radiation though, we have to note there’s still limited published data on the wavelength, dose, and duration of UVC radiation required to inactivate the SARS-CoV-2 virus. We need to wait for ongoing studies to give supporting evidence that UVC light is effective.
In addition, the Food and Drug Administration (FDA) notes some downsides and risks for using UVC light in general:
Exposure to some types of UVC light can damage your skin or eyes (this mainly refers to conventional UVC light; all existing evidence supports that far-UVC light is safe for human exposure).
The UVC light lamps sold for at-home use are often lower in intensity, so it may take longer to kill germs.
In the midst of a pandemic, there are many indoor spaces where people aren’t maintaining social distance— hospitals, buses, planes, trains, train stations, schools, restaurants, offices, theaters, and gyms are but a few examples. In all these places, it would be beneficial to have overhead far-UVC lights that continuously kill microbes including the COVID-19 virus, thus limiting the spread of the virus.
First though, we have to wait for more data to confirm that UVC light is an effective disinfection method, and completely safe to widely implement in human society.
About the Author: Isabel Zhang
Isabel is a senior in high school, and is interested in biology and engineering. In her free time, she loves to bake, sketch, and hang out with her family.
Cantor, C. (2020, April 21). Could a New Ultraviolet Technology Fight the Spread of Coronavirus? Retrieved from https://news.columbia.edu/ultraviolet-technology-virus-covid-19-UV-light
Center for Devices and Radiological Health. (2020, August 19). UV Lights and Lamps: Ultraviolet-C Radiation, Disinfection, and Coronavirus. Retrieved from https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/uv-lights-and-lamps-ultraviolet-c-radiation-disinfection-and-coronavirus
Seladi-Schulman, J. (2020, October 22). Can UV Light Kill the New Coronavirus? Retrieved from https://www.healthline.com/health/does-uv-kill-coronavirus#disadvantages