A promising way to fight coronavirus: with ultraviolet light
Lesson summary
Hi there, welcome back to another Plain English lesson. I’m Jeff; JR is the producer; and this is lesson number 288. That means our full and complete lesson is available online at PlainEnglish.com/288.
Coming up today: a novel way to attack the novel coronavirus: with ultraviolet light. Light is used as a disinfectant in some hospitals, so can it be used more broadly to fight the spread of the virus? We have an expression for you—it is “at once”—and a quote of the week. Let’s get going!
Power of disinfecting light
The coronavirus pandemic has set off a scramble to wash our hands, cover our mouths, and—those of you who work in public spaces know this better than anyone—to continuously sanitize high-traffic surfaces. If you’ve ever thought, “There must be an easier way,” then you might be right. What if it’s possible to fight the invisible coronavirus with a disinfectant that is invisible—namely, ultraviolet light?
Ultraviolet light has a wavelength of between 10 nanometers and 400 nanometers; it’s longer than X-Rays but shorter than visible light and it cannot be seen by humans. UV light can be both helpful and harmful. Much of the energy given off by the sun is ultraviolet radiation; that is what gives us a tan, what gives us skin cancer, and what produces vitamin D, an essential ingredient for building our bones.
At certain wavelengths, UV damages living cells. UV light with wavelength between 200 and 280 nanometers is called UV-C light. At a wavelength of 254 nanometers, it damages DNA: it makes it impossible for cells to make copies of themselves, arresting growth. Larger, complex mammals can sometimes repair damage done by UV-C light, though it is known to cause cancer. Viruses and bacteria are another story: they are killed immediately by exposure to UV-C.
That’s why hospitals have been using UV-C light as a disinfectant for about ten years. Some hospital rooms are equipped with large UV-C lamps that are turned on once nobody is in the room. It is a quick and deadly efficient way of disinfecting a large area all at once.
But it only works in rooms that can be equipped with the lights and can be safely cleared and secured; you don’t want someone accidentally wandering in. Because of the danger, it hasn’t been used in a localized way. By localized I mean, it hasn’t generally been used to disinfect a table or a surface or some other narrow spot. It has always been better to clean a smaller surface the old-fashioned way.
But the coronavirus, and advancements in technology, are starting to change the calculus. A team of roboticists in Ireland has developed a robot called Violet. (Never let it be said that scientists don’t have a sense of humor!) Violet uses motion detectors to determine if there are humans in an area, and then to direct the UV-C light only to where there are no humans. This makes it easier to disinfect hard-to-clean areas, such as bathrooms, waiting rooms, and the “nooks and crannies” of public spaces. It also improves safety for an often-overlooked population: the people who have to do the cleaning. If a robot can clean an area with ultraviolet light, then employees don’t have to expose themselves while attempting to clean an area for the rest of us.
Another type of UV-C light, at a wavelength of just 222 nanometers, is believed to be safe for humans. This type of light is absorbed by the outer layers of our skin and eyes, so it doesn’t do damage to humans. But researchers have discovered that this type of light—called far UV-C—still kills viruses and bacteria, including coronaviruses. A team at Columbia University in New York sprayed a mist full of coronaviruses in the air and then exposed that mist to a far-UV-C lamp. Within eight minutes, 90 percent of the airborne virus was killed; 99.9 percent was killed after just 25 minutes of exposure to the light.
The coronaviruses the researchers used were not the ones that are currently causing the pandemic, but they are similar, leading them to believe that far UV-C light would be effective against the novel coronavirus and safe for humans.
You can imagine, then, that high-traffic public places like shops, hair and nail salons, restaurants, gyms, public transportation, and offices might use far-UV-C to continuously disinfect high-traffic areas. The New York City subway system has begun investing in far-UV-C disinfecting lights.
Magnolia Bakery, a popular chain in New York, has begun installing a device that looks like a metal detector at the front doors of its cafés, where patrons will be bathed in invisible and disinfecting UV-C light as they walk in. Experts say this sort of thing is safe, but unlikely to make much of a difference: the virus doesn’t spread from being on your clothes or even your skin; it spreads from being ejected from your body into the air and onto surfaces like tables and doorknobs. The more effective use of the light would be to apply it to high-traffic surfaces, either continuously or in bursts.
A note of caution: far-UV-C light has not been found to do damage to humans and prolonged exposure has not done damage to mice, either. However, it’s not known whether humans would suffer from long-term continuous exposure to far-UV-C rays. Getting blasted with it once in a while may be safe, but it might be a different story to work under far-UV-C lights every day—or ride in a train with it.
Really safe?
The idea kind of creeps me out. The only reason far-UV-C rays are safe is that our outer layer of dead skin cells absorbs the light before it can harm the living cells. That doesn’t seem like a failsafe system! What if you just got an exfoliant scrub? Those are designed to scrape off the dead cells on the outside of your skin. You’d then lose all your protection against far-UV-C.
No thanks. I’ll skip my Magnolia Bakery cupcakes for now—besides, I get my New York cupcakes at Amy’s Bread.
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