FAU researchers show how far respiratory droplets from a cough can spread COVID-19

(WSVN) - Germs are invisible, but researchers at a South Florida university came up with a way to see how far someone with COVID-19 can spread the virus, and the visuals are disturbing. The Nightteam’s Brian Entin has our special report, “Super Spreaders.”

It’s the social distance we have heard about for months.

Officials: “Six feet apart, six feet apart.”

But is six feet really enough separation to keep a person with coronavirus from infecting others?

Dr. Manhar Dhanak, FAU: “We are seeing that the smallest droplets that are present in a cough can travel far.”

Researchers at Florida Atlantic University brought us into their Dania Beach lab to demonstrate how far the respiratory droplets of a cough can spread.

Dr. Sid Verma, FAU: “When we cough, we expel a large range of droplet sizes, so this fog would be comparable to the smallest droplets that we create when we actually cough or sneeze.”

For the experiment, scientists pump a heated mixture of water and glycerin through the mouth of a mannequin to simulate coughing.

When the lights go out, lasers illuminate what is normally invisible.

Researcher: “This is like a gentle cough.”

Now, watch what happens when they simulate a heavy cough.

The droplets race past three feet.

Brian Entin: “And it keeps traveling.”

Researcher: “Six feet, and you see some puffs already at nine feet.”

Brian Entin: “Nine feet?”

Researcher: “Correct, and they’re approaching 12 feet.”

Researchers found some particles reach double the recommended social distance in less than a minute.

Brian Entin: “With a heavy cough and the right air situation, it goes farther than people necessarily think. I think a lot of people think it’s just six feet.”

Professor Sid Verma, FAU: “That’s right, especially the smallest particles we saw here can travel as far as 12 feet.”

Brian Entin: “Now, we’re going to try the experiment with this homemade mask, put the mask on the dummy and see how far the simulated germs travel.”

The short answer: not nearly as far, whether it’s a high-quality homemade mask or a surgical-grade one.

Researcher: “And the smoke doesn’t even travel half a foot.”

Droplets still escape, but face coverings slow their speed and spread.

Professor Sid Verma: “As we saw, the masks make a huge difference, especially in the forward motion of the jets. We did notice some leakage from the sides, but the masks should still be able to capture the larger droplets.”

Still, experts say it’s not just coughing or sneezing that can pose problems in cramped, indoor spaces.

Professor Manhar Dhanak: “Breathing, talking, especially without a mask, these particles are so tiny, they can remain suspended for quite a bit of time.”

To show how air flow contributes to the spread of COVID-19, the CDC released this sketch of a restaurant from an outbreak in China.

The yellow circle represents one person with the virus, and you can see that one person was able to infect nine others across three tables.

With South Florida restaurants beginning to reopen, officials have capped indoor seating at 50% capacity and are encouraging more outdoor dining.

Brian Entin: “If you were going to go to a restaurant, maybe sitting outside would be a better choice, you think?”

Professor Sid Verma: “If it’s possible, yes, that would be a better choice.”

The key is to minimize your exposure to trouble spots because when tiny respiratory droplets are not from a mannequin, but from the mouth of a person who has COVID-19, what you can’t see could infect you.

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