【】

Airbnb needs people to feel safe. Since the coronavirus pandemic started, the company added new cleaning guidelines and a 72-hour buffer between stays.

Still, with more than 4.9 million coronavirus cases recorded around the world, people are understandably paranoid about staying in a stranger's home.

That's probably why you've seen ads for UV light products online, like wands that promise to kill viruses and bacteria. But just how effective are they?

The basics: UVA and UVB vs. UVC

Unlike UVA and UVB, UVC is absorbed completely by the atmosphere.Credit: Shutterstock / Siberian Art

There are several kinds of UV light, explained Andrea Armani, a professor of chemical engineering and material science at the University of Southern California.

UV radiation, or ultraviolet radiation, comes from the sun. But you can't see it, like visible light. Or feel it as heat, as you can with infrared radiation.

There are nuances among UVs, too. UVA, UVB, and UVC represent UV radiations of different wavelengths. Most of us are already familiar with long-wave UA rays and medium-wave UVB lights, Armani said — it’s why we tan and burn.

Unlike UA and UVB rays that reach the Earth's surface from the sun, UVC rays are completely absorbed by our atmosphere.

Can UV rays kill COVID-19?

Previous studies have shown that UVC works against some coronaviruses, but there isn't research yet about how it fares against COVID-19.Credit: Shutterstock / Nor GalSEE ALSO:Airport to use autonomous robots to blast floors with UVC light

The short answer: probably.

Long-wave UVA and medium-wave UVB rays can damage a virus. But it’s a slow process.

“Thermal destabilizations are much slower. They happen but they take longer,” Armani said. “UVC is a chemical rearrangement — so it can be fast.”

Armani explained that UVC rays are especially disruptive to fundamental building blocks of DNA and RNA. There's no research about how UVC fares against COVID-19 specifically. But previous studies show it works against other coronaviruses.

“Scientists are confident it will work against COVID-19 because it has a fairly similar RNA structure,” Armani said.

Things to consider before buying a UVC device

There are a few things you should consider before investing in a UVC wand or other UVC devices.

The first and most important thing to consider: safety. Armani said UVC can affect skin cells the same way it kills bacteria; it can cause mutations in them and lead to skin cancer. Looking at UVC lights can cause irreversible blindness, too, she added.

“You only get one chance at that, and a small mistake can be a lifelong burden for you,” Armani said. “It sounds great — you can put a UVC source in the middle of your den, turn it on, and come back later — except if you make a small mistake, you can’t undo it.”

"A small mistake can be a lifelong burden."

Armani suggests that you look for UVC devices that come with safety switches — automatic “turn-off” buttons that halt the light emission as soon as you're at risk of direct exposure.

Take extra caution when you're using a UVC wand, since you'll be in direct contact with the device. It might be tempting to look at that glowing neon blue light emitting from your UVC wand— but don't do it. Just don't.

The second thing to consider: the legitimacy of the product. Armani said she’s seen some counterfeit UVC consumer products on the market. But unless you have a device at home that measures wavelength in realtime (aka a spectrometer), there’s no way of distinguishing products that use UVC rays versus other UV rays.

Mashable Light SpeedWant more out-of-this world tech, space and science stories?Sign up for Mashable's weekly Light Speed newsletter.By signing up you agree to our Terms of Use and Privacy Policy.Thanks for signing up!

Armani suggested that FDA-approved UVC devices are going to be “a little more reputable" because they're thoroughly examined. But most are tailored toward industrial and medical facilities.

That's in part because the FDA generally examines UVC devices for medical claims — not commercial claims. Of course, the fact that UVC wands aren't FDA-approved doesn't mean that they aren't using UVC light. But you should make sure the product comes from a reputable company and has good reviews. Here are a few we found:

Credit: Monos

CleanPod UVC Sterilizer

Monos, $90

This UVC wand by Canadian luggage company Monos comes with a safety lock switch.

Credit: Hammacher Schlemmer

The Virus And Germ Destroying UV Wand

Hammacher Schlemmer, $149.95

This wand will automatically shut off its light if it's turned upward. 

Credit: UV-FIT

UVC Light Sanitizer Wand

UV-FIT, $64.99

UV-FIT's wand powers off automatically after 180 seconds to prevent accidental exposure. 

Using UVC wands to disinfect Airbnbs and homes

UVC can be an effective household disinfectant. But there are a few things you should pay attention to.Credit: Shutterstock / Nor Gal

So you got a legitimate UVC wand — what now? Sure, a UVC wand is easy to pack and can disinfect your Airbnb or hotel room, but the actual efficacy of a UVC wand depends on three things, Armani said:

• The intensity of the UVC bulb.

• The distance between the UVC light source and the infected surface.

• How long a surface is exposed to UVC light.

The longer and closer the UVC light source is to the surface, the more effective it is. More intense bulbs are more effective, too.

In any case, Armani said it's best to use a UVC wand alongside chemical cleaners or disinfectant wipes because they help get rid of large debris.

“I view UVC as a secondary. It’s a good secondary clean to remove any strays, viral or bacterial particulates that the initial, coarse chemical clean left behind,” she said. “If you ever think about that 99.9-percent [disinfectant rate] on your chemical clean, UVC can kind of go back and get that 0.01 percent.”

For one, UVC wands are relatively compact and only cover one small patch at at a time. That means it's going to takeforeverto clean the entire Airbnb effectively with just a wand.

Plus, you'll need 30 seconds of UVC exposure for every 2-by-6-inch area, Armani said. Now, imagine doing that for an entire room or an entire Airbnb with just a wand — yea, it's a lot of time and work.

UVC light can't remove dirt or clumps either, Armani added. Disinfectant wipes can.

Still, there are a few things UVC wands can do for your Airbnb that wipes can't: clean fabric surfaces like couches and beds.

Overall, the combination of a UVC wand and a chemical cleaner can make for an effective cleaning regimen when you're staying at an Airbnb or a hotel. But chances are, you're not going to get to every nook and cranny no matter how hard you or the host try.

Which makes this as good a time as ever to remind you that the Center for Disease Control and Prevention continues to recommend that you stay home to prevent the spread and contraction of COVID-19.

But if your trip and your Airbnb stay is absolutely essential, it might be a good idea to pack a UVC light wand along with some disinfectant wipes so you can get that Airbnb as clean as possible.

TopicsHealthAirbnbCOVID-19

(责任编辑：焦點)