Outside airflow helps to reduce the chance of getting COVID-19, but people still need to maintain proper social distancing

By Julie Mazziotta
May 18, 2020 01:27 PM
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A father and daughter walk in a New Jersey park

With Memorial Day weekend on the horizon, warm weather ahead and many states lifting stay-at-home restrictions, Americans are itching to get outdoors — and that may not be a bad thing, according to new research on COVID-19 transmission and many health experts.

According to a study out of China, the risk of getting the new coronavirus while outdoors is extremely low. Of 7,324 COVID-19 cases in China, just one was transmitted outdoors. In that case, a 27-year-old contracted the virus after speaking to a person who had recently returned from Wuhan, the site of the first COVID-19 outbreak, while outside. All of the other cases were traced back to indoor transmission.

“The transmission of respiratory infections such as SARS-CoV-2 from the infected to the susceptible is an indoor phenomenon,” the researchers concluded.

Former Food and Drug Administration commissioner Dr. Scott Gottlieb shared the study on Twitter on May 6 and advocated for resuming activities outdoors.

“Studies suggests activities held outdoors as temperatures warm pose lower COVID risk than those done in confined indoor spaces,” he tweeted. “As we reopen, states should look to ease rules to allow more recreational, religious, and business activities to occur outside.”

Health experts say that outside airflow helps to disperse the virus.

“It definitely spreads more indoors than outdoors,” Roger Shapiro, a professor at Harvard University's T.H. Chan School of Public Health, told The Hill. “The virus droplets disperse so rapidly in the wind that they become a nonfactor if you're not really very close to someone outdoors — let’s say within six feet.”

That isn’t to say that there isn’t a risk — there are the few cases where outdoor transmission occurred, and if people do not continue to take precautions like wearing a mask and staying six feet apart, they could contract COVID-19.

“The risk is lower outdoors, but it’s not zero,” Shan Soe-Lin, a lecturer at the Yale Jackson Institute for Global Affairs, told The New York Times. “And I think the risk is higher if you have two people who are stationary next to each other for a long time, like on a beach blanket, rather than people who are walking and passing each other.”

While a recent study (not specifically about COVID-19) found that smaller respiratory droplets can hang in the air for more than eight minutes, it was conducted indoors. Researchers have noted that smaller respiratory droplets — like those from breathing versus ones from sneezing or coughing — are likely not enough to transmit COVID-19 in an outdoor space with proper social distancing.

“The virus load is important,” Eugene Chudnovsky, a physicist at Lehman College and the City University of New York’s Graduate Center, told the Times. “A single virus will not make anyone sick; it will be immediately destroyed by the immune system. The belief is that one needs a few hundred to a few thousand of SARS-CoV-2 viruses to overwhelm the immune response.”

Now, as parks and beaches begin to reopen, going outside should be low-risk and even necessary for mental health, as long as precautions are taken. People should continue to stay with just the people they are quarantining with and six feet apart from others, and wear masks if that is not possible. It is important to keep in mind that even if a person is not showing symptoms, they may still have COVID-19, and could infect others.

“You can go to the beach, you can go to the park, and it can be safe,” Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, told The Hill. “It’s just you have to be cognizant of the fact that the virus is there.”

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