How a focus on cleaning surfaces can distract from actual virus spread

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• Judy Woodruff:

  As we have been mentioning, the U.S. has passed yet another tragic marker in the pandemic.

  More than 200,000 people have died in this country from COVID-19 and related complications. That, in a period of less than eight months, is nearly twice as many Americans who have been killed in every major conflict since the Korean War combined.

  Our understanding of how the coronavirus is spreading continues to evolve. We want to use this moment to clarify much of the latest scientific thinking.

  First, a report from Stephanie Sy, followed by a conversation with William Brangham.

• Woman:

  The coronavirus can remain infectious on plastic and steel surfaces for up to three days.

• Woman:

  That has many people worried about shopping and other everyday tasks.

• Man:

  Because you have got to be putting that disinfectant on these groceries.

• Stephanie Sy:

  This was the sound of fear early in the pandemic, after studies showed that the novel coronavirus could live on surfaces for hours, even days.

  It led to a furious wave of scrubbing, disinfecting and sold-out cleaning supplies across the country.

• Emanuel Goldman:

  But the problem with those experiments is that they didn't relate to what a real-life scenario would be like.

• Stephanie Sy:

  That's Dr. Emanuel Goldman, a microbiologist at Rutgers New Jersey Medical School.

  In July, he published this article in the British medical journal "The Lancet" arguing that these early studies greatly exaggerated the amount of virus that could actually be found on surfaces in the real world. He pointed out that the lowest amount of infectious particles researchers used to test surfaces in the lab was 10,000, a huge amount.

• Emanuel Goldman:

  You would need something like 100 people coughing or sneezing on the same small surface area to get anywhere near the amount of virus that they used in these experiments.

• Stephanie Sy:

  He says these mistakes, and a lack of scrutiny, have siphoned limited resources from everything from subway systems to schools for excessive deep cleaning that shows little evidence of helping prevent COVID spread.

• Emanuel Goldman:

  Our mothers taught us, you go to the bathroom, you wash your hands. You prepare food, you wash your hands. You touch something dirty, you wash your hands. That's all you have to do.

  Normal, routine hygiene is sufficient to protect against this virus.

• Stephanie Sy:

  Meanwhile, he adds, not enough money and attention have been paid to what we now know is the primary way the virus travels: the air.

• Emanuel Goldman:

  A teacher from a school system saying they were going to shut down the schools one day a week for deep cleaning and disinfection. Wouldn't it be better to use it instead on ventilation systems or hiring more teachers, so you could have fewer students per class?

• Shelly Miller:

  You want to try to replicate the outside, indoors, in your space.

• Stephanie Sy:

  Dr. Shelly Miller is an environmental engineer at the University of Colorado Boulder. For decades, she's studied the way pollutants and infectious diseases spread in indoor spaces, and over the summer helped her own university prepare for when students and faculty return to campus.

• Shelly Miller:

  You want to control the source of the contaminants. And, in this pandemic, the sources are the infectious people inside. And so, to control the release of virus, you want to wear a mask, and you also want to be outside of their personal cloud.

  But some of the virus can potentially leak into the environment, and then you have to clean the environment. And the way to do that is the filtration and ventilation.

• Stephanie Sy:

  The simplest way to do that, she says, open a door or window.

  But in many parts of the country where it's still too hot, or becoming too cold, to do that, Miller says there are different ways to increase a building's mechanical ventilation and filtration.

  Here's a basic guide: Buildings up to code should already be replacing the inside air with outside air three times an hour. But with coronavirus, that should be doubled, to six exchanges per hour, and, ideally, to nine exchanges per hour.

  And, crucially, the more people there are contained in a space, the more exchanges are needed. HEPA filters, which stands for high-efficiency particulate air, should also be added to ventilation systems to increase protection.

  If I walk into a restaurant or a classroom, is there a way for me to personally tell if that is a safe place to be, if there's enough ventilation?

• Shelly Miller:

  Unfortunately, at this point in time, no. And that is why, a lot of times, I have been saying, well, we really need to address this. We need to give buildings and classrooms and other facilities resources, so they can — so they can let the public know how they have attended to this.

• Stephanie Sy:

  She and others say the Centers for Disease Control and Prevention and the World Health Organization have been too slow to move away from early guidance on surface disinfection, and towards clearer guidance on preventing airborne transmission.

  Last Friday, the CDC did add language on its Web site about aerosols from coughing or breathing spreading the virus, and the need for ventilation, then suddenly removed it.

• Shelly Miller:

  So, the only rule of thumb I can say is, if you walk into a space and it feels hot and stuffy in there, and you can smell smoke and you can smell different odors, then it's probably not ventilated enough, and you probably shouldn't spend very much time in there.

• Stephanie Sy:

  Even portable air cleaners can help, and Dr. Miller and her colleagues have created a guide for schools on these, which you can find on our website. The bottom line: If you're thinking about going back to the gym, to a restaurant, your office or school, keep washing your hands, keep wearing your mask, and keep social distancing. But don't let those deep cleans fool you. Ask what they have done about the air.

• Emanuel Goldman:

  The problem is that it's been out there for so long, and Shakespeare said it the best, what's done cannot be undone. And it's going to be a long time to turn the ship around, if ever, because a lot of people still are operating on these assumptions.

• Stephanie Sy:

  For the "PBS NewsHour," I'm Stephanie Sy in Phoenix.