Still Disinfecting Surfaces? It Might Not Be Worth It

Early in the pandemic, people were advised to disinfect everything they touched. But now that scientists understand more about how COVID-19 spreads, all that scrubbing down may have been overkill.

Transcript

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.

PATTI 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.

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