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Still Disinfecting Surfaces? It Might Not Be Worth It

Dec 28, 2020
Originally published on December 28, 2020 1:58 pm

At the start of the pandemic, stores quickly sold out of disinfectant sprays and wipes. People were advised to wipe down their packages and the cans they bought at the grocery store.

But scientists have learned a lot this year about the coronavirus and how it's transmitted, and it turns out all that scrubbing and disinfecting might not be necessary.

If a person infected with the coronavirus sneezes, coughs or talks loudly, droplets containing particles of the virus can travel through the air and eventually land on nearby surfaces. But the risk of getting infected from touching a surface contaminated by the virus is low, says Emanuel Goldman, a microbiologist at Rutgers University.

"In hospitals, surfaces have been tested near COVID-19 patients, and no infectious virus can be identified," Goldman says.

What's found is viral RNA, which is like "the corpse of the virus," he says. That's what's left over after the virus dies.

"They don't find infectious virus, and that's because the virus is very fragile in the environment — it decays very quickly," Goldman says.

Back in January and February, scientists and public health officials thought surface contamination was a problem. In fact, early studies suggested the virus could live on surfaces for days.

It was assumed transmission occurred when an infected person sneezed or coughed on a nearby surface and "you would get the disease by touching those surfaces and then transferring the virus into your eyes, nose or mouth," says Linsey Marr, an engineering professor at Virginia Tech who studies airborne transmission of infectious disease.

So people were advised to clean common areas with disinfectant, wipe down cans and boxes from the grocery store and even wear gloves.

In retrospect, Marr says that was "overkill." Today, she says, "all the evidence points toward breathing in the virus from the air as being the most important route of transmission."

Scientists now know that the early surface studies were done in pristine lab conditions using much larger amounts of virus than would be found in a real-life scenario.

Even so, many of us continue to attack door handles, packages and groceries with disinfectant wipes, and workers across the U.S. spend hours disinfecting surfaces in public areas like airports, buildings and subways.

There's no scientific data to justify this, says Dr. Kevin Fennelly, a respiratory infection specialist with the National Institutes of Health.

"When you see people doing spray disinfection of streets and sidewalks and walls and subways, I just don't know of any data that supports the fact that we're getting infected from viruses that are jumping up from the sidewalk."

Marr says focusing on cleaning surfaces is not the best way to slow infection.

"Instead of paying so much attention to cleaning surfaces, we might be better off paying attention to cleaning the air, given the finite amount of time and resources," Marr says.

Fennelly agrees, noting that airborne transmission is more likely in indoor public places like restaurants.

"Why aren't we doing more to figure out ways to ventilate those areas?" he asks. "It would be better to use ultraviolet germicidal irradiation, which we know can kill these viruses in the air."

Figuring out how to prevent coronavirus transmission in office buildings, schools, bars and restaurants is definitely a challenge, he says, but "we have a lot of really smart engineers and architects and industrial hygienists who know how to handle airborne infection."

Spraying disinfectant is not only unproductive, but it's potentially dangerous, according to Delphine Farmer, an atmospheric chemist at Colorado State University.

Heavy use of disinfectants, like bleach and hydrogen peroxide, can "produce toxic molecules that then we breathe," she warns.

And breathing in toxic particles can affect our health, Farmer says. The molecules can react directly with the cells in lung tissue and cause oxidative stress. And certain molecules are known to be toxic. "It's like breathing in poison," she says.

Early on in the pandemic, Farmer says, many people were making cleaning mistakes: "There were a lot of cases of people cleaning their groceries with bleach and vinegar, which is a recipe to create some very nasty chlorine gas, and people were getting quite ill from those side effects."

Bottom line: Health experts emphasize that the most important way to avoid infection is to stay away from crowds and wear a mask whenever you leave the house. Limit the time you spend in any indoor space with people outside of your own household — and wear a mask when you're in those spaces.

When you're out in public, be aware of surfaces you touch, and wash your hands often. It's much more effective to wash your hands thoroughly than try to clean everything you touch.

And if you do decide to keep wiping down canned goods or packages that arrive at your house, there's no need for fancy cleaning products; "old-fashioned soap and water" will do just fine, Farmer says.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

DAVID GREENE, HOST:

So at the start of the pandemic, we were all told to wipe down surfaces. Remember? Well, it turns out all that disinfecting might not be necessary. Here's NPR's Patti Neighmond.

PATRICIA NEIGHMOND, BYLINE: If a person infected with the coronavirus sneezes, coughs or talks loudly, droplets containing particles of the virus can land on nearby surfaces. But Rutgers University microbiologist Emanuel Goldman says recent studies find the risk of getting infected from touching a contaminated surface is low.

EMANUEL GOLDMAN: In hospitals, surfaces have been tested near COVID patients, and no infectious virus can be identified.

NEIGHMOND: What's found is viral RNA, which he says is like the corpse of the virus, what's left over after it dies.

GOLDMAN: They don't find an infectious virus. And that's because the virus is very fragile in the environment. It decays very quickly.

NEIGHMOND: But back in January and February, Linsey Marr, an engineering professor at Virginia Tech who studies airborne transmission of infectious disease, says scientists didn't know this. In fact, early studies indicated the virus could live on surfaces for days. And it was assumed, Marr says, that this could lead to infection when people coughed or sneezed.

LINSEY MARR: These large droplets that you can see that might land on our groceries or land on the table and that you would get the disease by touching those surfaces and then transferring the virus into your eyes, nose or mouth.

NEIGHMOND: Which is why people were advised to scrub common areas with disinfectant, wipe down cans and boxes from the grocery store and even wear gloves. In retrospect, Marr says, that was overkill.

MARR: All the evidence points toward breathing in the virus from the air as being the most important route of transmission.

NEIGHMOND: And scientists now know the early surface studies were done in pristine lab conditions using much larger amounts of virus than would ever be found in a real-life scenario. Even so, workers nationwide are disinfecting surfaces in large public areas. Respiratory infections specialist Dr. Kevin Fennelly with the National Institutes of Health says there's just no scientific reason to do this.

KEVIN FENNELLY: When you see people doing spray disinfection of streets and sidewalks and walls and subways, I don't know of any data that supports the fact that we're getting infected from viruses that are jumping up from the sidewalk.

NEIGHMOND: Better to focus effort and money, he says, reducing airborne transmission, which we know occurs in public places like bars and restaurants.

FENNELLY: Why aren't we doing more to figure out ways to ventilate those areas better, to use ultraviolet germicidal radiation, which we know can kill these viruses in the air?

NEIGHMOND: Spraying disinfectant is not only unproductive, Delphine Farmer, an atmospheric chemist at Colorado State University, says it's dangerous.

DELPHINE FARMER: When you use a lot of these disinfectants, like bleach and hydrogen peroxide, they can do chemistry, and that chemistry produces toxic molecules that then we breathe.

NEIGHMOND: Which can affect our health.

FARMER: Those molecules will - some of them may react directly with the cells in your lung tissue and cause a lot of oxidative stress. Others are just known to be toxic. It's breathing in poison.

NEIGHMOND: So at home, if you want to wipe down your cans and packages, there's no real harm in it. Just use soap and water. And remember the most important way to avoid infection - stay away from crowds, and whenever you leave the house, wear a mask. And wash your hands often, says microbiologist Goldman. You're better off washing your hands than cleaning surfaces.

Patti Neighmond, NPR News.

(SOUNDBITE OF FEVERKIN'S "JUNE") Transcript provided by NPR, Copyright NPR.