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Air Flow May Have Caused COVID-19 Spread In a Restaurant, Study Shows

Inside a restaurant with social distancing in place. Diners are at tables alone and not in focus. A waiter is wearing a face mask and gloves.

chee gin tan / Getty

Key Takeaways

  • A study from South Korea linked three new COVID-19 infections to a single person at a restaurant.
  • Researchers discovered that an air conditioner blew SARS-CoV-2 droplets around the restaurant.
  • The study's authors are urging restaurants to be more mindful of their indoor airflow.

A new study from researchers in South Korea details how one COVID-19 outbreak at a restaurant managed to impact people who didn’t have close contact with an infected person.

The study, which was published in the Journal of Korean Medical Science on November 23, analyzed a small outbreak that occurred in June in the city of Jeonju. The outbreak caused three infections at a restaurant within a short time.

The researchers used personal interviews, data collection on closed-circuit TV images, and cell phone location data to map out where people were seated in the restaurant. Then, they studied airflow direction and velocity, the distance between people who were infected, and how often the people moved.

The researchers discovered that a person infected with COVID-19 was seated near a “ceiling-type” air conditioner, which blew droplets containing SARS-CoV-2 (the virus that causes COVID-19) toward the other people in the restaurant.

The droplets traveled more than 21 feet around the restaurant, and the virus moved fast. In one instance, the initial infected person was only in the restaurant for five minutes with a person who later tested positive for COVID-19. In another, a person who later tested positive was seated 15 feet away from the infected person.

The researchers concluded that “droplet transmission can occur at a distance greater than 2 meters [6.5 feet] if there is direct airflow from an infected person."

Based on the findings, the authors recommended "updated guidelines involving prevention, contact tracing, and quarantine for COVID-19" to control the spread of the disease.

Previous Studies Had Similar Findings

In July, a study published in the journal Emerging Infectious Diseases detailed how one diner with COVID-19 infected nine other people at a restaurant in Guangzhou, China. The original patient did not have symptoms at the time.

The researchers discovered that the restaurant’s air conditioners blew SARS-CoV-2 particles around the dining room—including to people at tables on either side of the original patient

However, not every person who was there got sick: 73 other diners who ate in the same area of the restaurant on that day did not become infected, and neither did the eight employees who were working on that particular floor of the restaurant.

The researchers wrote: “We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation" and noted that the direction of airflow was “the key factor for infection.”

To prevent the spread of COVID-19 in restaurants, the researchers recommend "strengthening temperature-monitoring surveillance, increasing the distance between tables, and improving ventilation.”

Is Indoor Dining Safe?

Currently, the Centers for Disease Control and Prevention (CDC) urges people to sit outside when dining out whenever they are able, and to take precautions like social distancing from other diners and wearing a mask “as much as possible when not eating.”

Amesh Adalja, MD

There’s always going to be some level of risk. You cannot eat with a mask on.

— Amesh Adalja, MD

While the new airflow study and its predecessor are concerning, infectious disease expert Amesh Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security, tells Verywell that “it’s not the normal way people are getting infected."

Adalja does say that the research highlights that restaurants should consider airflow when they seat people. “They probably should not be seated in the direct path of a major air current."

Peter Winkelstein, MD, executive director at the Institute for Healthcare Informatics at the University at Buffalo, tells Verywell that indoor dining is too risky. “You should steer clear. We know for sure that indoors is more dangerous than outdoors when it comes to COVID-19. And, if you’re in an indoor setting where you cannot wear a mask…that’s clearly a very dangerous situation.”

Adalja says that even if indoor dining "can be done relatively safely, there are going to be these odd situations of small outbreaks.” Therefore, a lot of it comes down to risk tolerance.

"If patrons are being screened, servers are wearing masks, plexiglass is put in place where you think there will be an issue, that will decrease the risk,” Adalja says. “But there’s always going to be some level of risk. You cannot eat with a mask on.”

What This Means For You

Air conditioners and airflow in the building have been linked to COVID-19 outbreaks at restaurants. If you dine out, try to be mindful of where the airflow is coming from relative to your seat. If COVID-19 is spreading in your community, consider that it might be very risky to go out to eat.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. Kwon K-S, Park J-I, Park YJ, Jung D-M, Ryu K-W, Lee J-H. Evidence of long-distance droplet transmission of sars-cov-2 by direct air flow in a restaurant in koreaJ Korean Med Sci. 2020;35(46):e415.

  2. Lu J, Gu J, Li K, Xu C, Su W, Lai Z, et al. Covid-19 outbreak associated with air conditioning in restaurant, guangzhou, china, 2020. Emerg Infect Dis. 2020;26(7):1628-1631. doi:10.3201/eid2607.200764

  3. Centers for Disease and Prevention (CDC). Personal and social activities. Updated October 29, 2020.