Expert Pitch
Washington University in St. Louis

WashU Expert: Forget plexiglass, debaters just need 4.5 feet, smart airflow

Two people, facing each other, talking — let’s call it “excitedly” — are probably the most important ingredients for a debate. They are also a recipe for disaster if one of those two people has a highly contagious virus that has been shown time and again to be transmitted through the air.

Taking a cue perhaps from South Carolina Sen. Lindsey Graham’s Democratic challenger Jamie Harrison in an Oct. 3 debate, the vice presidential debate Oct. 7 featured plexiglass barriers intended as a protective measure against the spread of SARS-CoV-2, the virus responsible for COVID-19. But it isn’t enough, counsels an aerosols expert.

Aerosol expert Professor Biswas

“The shields are good if you have someone directly in front of you, and you are talking into it,” said Pratim Biswas, department chair and the Lucy & Stanley Lopata Professor in the Department of Energy, Environmental & Chemical Engineering at Washington University in St. Louis.

Otherwise, he said, particles just flow around them.

Biswas and researchers in his lab at the McKelvey School of Engineering have been using models to understand the different ways in which virus particles move around in a closed space.

Their most recent efforts, led by doctoral student Sukrant Dhawan, show that — like putting up a plexiglass barrier — “common sense” solutions don’t always cut it when it comes to COVID-19. This is true particularly in a setting where an infected person and a non-infected person are facing each other, talking.

Plexiglass barriers won’t do much, but you also don’t need excessive distance between debaters. In fact, as long as the airflow is controlled, the safest distance between the two participants would be anything beyond about 4.5  feet.

This is one of a few surprises when it comes to what activities do — or don’t — carry high risk of infection.

“People say that speaking will not lead to airborne infection because the droplets emitted are lower in concentration than if you were coughing or sneezing,” Dhawan said. “But when you talk, you generally talk for longer periods of time.”

In fact, modeling shows that when standing about 8 feet apart, facing each other, the risk of being infected by a cough is less than 30%. At that same distance, there is more than a 40% chance of being infected by an infected person talking for a minute. And if they talk for 10 minutes, the risk is nearly 100%.

Certainly, that risk can be mitigated by airflow dynamics. “Wind blowing from an infected person is the most high-risk situation,” Dhawan said. Viral particles can travel farther, infecting the unsuspecting. “At least, that’s what we assumed initially.”

Yes, droplets can absolutely travel farther when carried by a wind, but they don’t stop when they sense the presence of a healthy person. They continue to whiz by.

“The faster the wind, the less amount of time you are exposed to the droplets,” Dhawan said. “Actually, increasing wind velocity decreases risk.”

Of course, the best case scenario would be to have the wind blowing from the uninfected person to the infected person. But what if you don’t know who’s who?

If wind velocity is about .5 meters per second in the direction of the person exhaling, these droplets can’t go further than 4.5 feet. “There is zero risk beyond that distance,” Dhawan said.

As long as the debaters are at least four and a half feet apart with airflow directed back at them (and a properly functioning air filtration system), the risk of infection is minimal to none.

With “common sense” leading us astray, however, and caveats upon caveats, it is reassuring to note that there is still one place in which common sense does intersect with reality for most of us.

An infected person wearing a mask dramatically decreases the likelihood of infecting others.

In fact, at a distance of about 8 feet, an infected person coughing and speaking and, to a lesser degree, sneezing, is nearly as effective at preventing infection as if both people were wearing masks.

And since people infected with the SARS-CoV-2 virus do not always have symptoms, “the best thing, always,” Biswas said, “is to wear a mask.”




Filters close

Showing results

110 of 4146
Newswise: Long-Term Impacts of COVID-19: Your Mental Health
Released: 25-Nov-2020 2:15 PM EST
Long-Term Impacts of COVID-19: Your Mental Health
Cedars-Sinai

The COVID-19 pandemic has shaped more than half a year of our lives, canceling plans, upending livelihoods and causing feelings of grief, stress and anxiety. And Cedars-Sinai mental health experts say the pandemic could be shaping our mental health well into the future.

Released: 25-Nov-2020 12:45 PM EST
SARS-CoV-2 mutations do not appear to increase transmissibility
University College London

None of the mutations currently documented in the SARS-CoV-2 virus appear to increase its transmissibility in humans, according to a study led by UCL researchers.

Newswise: COVID-19 vaccine candidate tested preclinically at UAB nears first clinical test in people
Released: 25-Nov-2020 11:05 AM EST
COVID-19 vaccine candidate tested preclinically at UAB nears first clinical test in people
University of Alabama at Birmingham

Maryland-based Altimmune Inc., a clinical stage biopharmaceutical company, has submitted an Investigational New Drug, or IND, application to the United States Food and Drug Administration to commence a Phase 1 clinical study of its single-dose intranasal COVID-19 vaccine candidate, AdCOVID.

Released: 25-Nov-2020 11:05 AM EST
BIDMC researchers reveal how genetic variations are linked to COVID-19 disease severity
Beth Israel Lahey Health

New research BIDMC-led sheds light on the genetic risk factors that make individuals more or less susceptible to severe COVID-19.

Newswise: blog-pandemic-scenario-planning-lg-feature2.jpg
Released: 25-Nov-2020 11:05 AM EST
Pandemic Ups Game on Scenario Planning in The Arts
Wallace Foundation

Researcher/Author of new toolkit and report seeks to help arts and culture organizations add scenario planning to their strategic toolbox

Released: 25-Nov-2020 10:30 AM EST
Young people's anxiety levels doubled during first COVID-19 lockdown, says study
University of Bristol

The number of young people with anxiety doubled from 13 per cent to 24 per cent, during the early stages of the COVID-19 pandemic and lockdown 1, according to new research from the University of Bristol.

Newswise: 249837_web.jpg
Released: 25-Nov-2020 10:20 AM EST
Tracking COVID-19 trends in hard-hit states
Louisiana State University

Currently, there are over 10 million confirmed cases and more than 240,000 casualties attributed to COVID-19 in the U.S.

Released: 25-Nov-2020 9:55 AM EST
More Health Systems Join National #MaskUp Campaign
Cleveland Clinic

Many more health systems are joining the national #MaskUp campaign encouraging Americans to stop the spread of COVID-19 by following safety guidelines. Over just a few days, another 19 health systems with hundreds of hospitals united with 100 health systems nationwide with hospitals numbering in the thousands. The public service campaign is critical to the health and well-being of all Americans. It is a plea from healthcare professionals everywhere: wear a mask and follow other precautions to save lives and help get our country back on its feet.

Newswise: delaterre_jpeg.jpg
Released: 25-Nov-2020 7:35 AM EST
Warwick scientists design model to predict cellular drug targets against Covid-19
University of Warwick

The covid-19 virus, like all viruses relies on their host for reproduction

access_time Embargo lifts in 2 days
Embargo will expire: 30-Nov-2020 10:00 AM EST Released to reporters: 24-Nov-2020 5:35 PM EST

A reporter's PressPass is required to access this story until the embargo expires on 30-Nov-2020 10:00 AM EST The Newswise PressPass gives verified journalists access to embargoed stories. Please log in to complete a presspass application. If you have not yet registered, please Register. When you fill out the registration form, please identify yourself as a reporter in order to advance to the presspass application form.


Showing results

110 of 4146

close
1.22182