Piotr Malecki / Panos Pictures / R​edux

Updated at 12:08 a.m. ET on May 26, 2020.

COVID-19 has mounted a sustained attack on public life, especially indoor life. Many of the largest super-spreader events took place inside—at a church in South Korea, an auditorium in France, a conference in Massachusetts. The danger of the indoors is more than anecdotal. A Hong Kong paper awaiting peer review found that of 7,324 documented cases in China, only one outbreak occurred outside—during a conversation among several men in a small village. The risk of infection indoors is almost 19 times higher than in open-air environments, according to another study from researchers in Japan.

Appropriately, just about every public indoor space in America has been shut down or, in the case of essential businesses such as grocers, adapted for social-distancing restrictions. These closures have been economically ruinous, transforming large swaths of urban and suburban life into a morbid line of darkened windows.

Today, states are emerging from the lockdown phase of the crisis and entering a queasy period of reopening. But offices, schools, stores, theaters, restaurants, bars, gyms, fitness centers, and museums will have no semblance of normalcy until we learn how to be safe—and feel safe—inside.

To open these spaces, we must be guided by science and expertise. Fortunately for us, researchers are discovering the secrets of how COVID-19 spreads with a combination of clever modeling and detective work.

Before we review the relevant studies and draw out lessons for the future of the great indoors, a brief word of humility. Our understanding of this disease is dynamic. Today’s conventional wisdom could be tomorrow’s busted myth. Think of these studies not as gospels, but as clues in a gradually unraveling mystery.

1. COVID-PROOF THE OFFICE

On March 8, South Korean public-health officials learned of a COVID-19-positive patient working in a call center in downtown Seoul. The office was located in one of the densest parts of the city, on the 11th floor of a 19-story mixed-use building with hundreds of offices and apartments. More than 1,000 people worked or lived in the building, sharing several elevators and a lobby. The possibility of mass infection was high.

But investigators found that the outbreak was surprisingly concentrated. Of the 97 people in the building who tested positive for the disease, 94 worked on one floor—in the call center. Of those 94, all but a handful worked in one densely packed phone bank. On one side of the floor, the disease was transmitted to two-thirds of employees. But less than 5 percent of the rest of the floor tested positive, as did less than 1 percent of the remainder of the building.

A floor plan of the site of a coronavirus outbreak in Seoul, South Korea. The blue seats show where people with confirmed cases sat. (Courtesy of the Centers for Disease Control and Prevention)

In its conclusion, the Korean CDC writes that the spread of the virus was almost entirely limited to the one floor “despite considerable interaction between workers on different floors in the elevators and lobby.” This would suggest that the main facilitator wasn’t common touch points, such as doors and elevator buttons, but rather common airspace. When people talk—or sneeze or cough—they produce respiratory droplets that can come to rest in other people’s mouths, noses, and lungs. Talking for hours in close quarters, in an unventilated space, can create an ideal petri dish for COVID-19 transmission.

It would be irresponsible to use the Korean study an an illustrative example if it were an outlier. But its main finding is fully in line with the emerging scientific consensus. On Thursday, the Centers for Disease Control and Prevention updated its summary of COVID-19 transmission to clarify that the virus “does not spread easily” from touching surfaces or objects—like, say, elevator buttons. Instead, they wrote, “the virus is thought to spread mainly from person-to-person … through respiratory droplets.”

[ Derek Thompson: What’s behind South Korea’s COVID-19 exceptionalism? ]

What does the science of indoor transmission mean for the future of the white-collar workplace? In a document shared with the World Bank, the South Korean government set out a 50-point plan for making offices safer. Masks are recommended for all employees. Desks and chairs are to be spread out or arranged in a “chess” or zigzag pattern so that no two individuals are sitting directly across from each other. Cubicles stage a triumphant return, as partitions between co-workers become necessary to block the vocal spray from coughs, sneezes, and loud phone conversations. As for small gatherings, live workshops, and corporate dinners? You can forget about these mixtures of work and social life. “Return home soon after work,” the Korean government advises. Long walks outside may replace the water cooler.

Office meetings, once merely obnoxious, are deemed simply noxious. The South Korean government devotes a full page and 12 bullet points to the subject of meetings, but those recommendations can be boiled down to three words that will make meeting-haters rejoice: fewer, smaller, shorter. For meetings that are necessary, large, and long, South Korea recommends masks for all participants and, if possible, open windows. Ventilation, in general, will become a watchword. Many offices may have to overhaul their vent technology or hire professionals to improve airflow throughout the entire office.

Most of these changes would amount to an earthquake for corporate culture, making the office less social, interactive, and serendipitous, and more like the amalgamation of many private workstations. Until we have a vaccine, and perhaps even after, many workers may determine that if they’re going to feel as alone in the office as they do at home, there’s no point to commuting in the first place.

The future is uncertain, and alternative scenarios are possible, especially if offices adopt widespread tests and temperature checks for months or years before the broad administration of a vaccine. These tests, while strict, might make some people feel safer inside the office than in any other public venue that lacks similar health transparency. With the confidence that work is the safest place other than their own home, some employees might treat the office as a multipurpose isolation unit. Drinking at work, under the protective shield of temperature checks, would make for a safer coronavirus-era ritual than gathering colleagues at an actual bar.

2. COVID-PROOF THE RESTAURANTS

On January 24, a Chinese family of five sat down to lunch in a crowded restaurant in Guangzhou, the most populous city in southern China. They had arrived in the city the previous day from Wuhan. It was a balmy afternoon in Guangzhou, with mid-day temperatures rising into the high 70s, and the restaurant on the third floor of a five-story building was buzzing with more than 80 patrons and no windows. The family gathered around a table along the back wall, between two local families, as an air conditioner pumped cool air across the three tables.

When they left the restaurant, a member of the family felt a fever coming on and, after checking into the hospital, received a diagnosis of COVID-19. Within two weeks, multiple people from each of the three tables—and 10 lunch patrons from the Guangzhou restaurant in total—had been diagnosed with the disease.

When the Guangzhou Center for Disease Control and Prevention investigated the matter, it published a diagram that told a simple story: One asymptomatic person in a restaurant had infected nine others in the direct path of the air conditioner. None of the dozens of other patrons or servers got sick.

A floor plan of restaurant tables and air-conditioning flow at the site of a coronavirus outbreak in Guangzhou, China. The yellow circle indicates an infected patient; red circles show future patients. (Courtesy of the Centers for Disease Control and Prevention)

It seemed to the researchers that the vector of transmission in the restaurant wasn’t a plate of food, an elevator button, or any matter of human touching, but air. Strong airflow from the AC unit had ferried coronavirus-poisoned droplets from table to table. “We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation,” the researchers wrote.

Many of the necessary interventions for restaurants will adhere to the same philosophy that guides the reimagining of the office. Masks may become commonplace on servers, as might barriers between tables. In an interview with The Atlantic, the chef and restaurateur Tom Colicchio suggested reducing interactions between patrons and waiters by asking diners to order their meals online before they arrive or on tablets at the table, like in an airport. Social distancing in the kitchen might mean fewer chefs, which could make complex dishes and extravagant plating impossible.

“Until there’s a vaccine, I don’t think dine-in restaurants will get back to normal in this country,” Steve Salis, a restaurant owner in Washington, D.C., told me. “We could introduce things like finger bowls or hand wipes, like you have at some Japanese restaurants, but for every cuisine. We could add public sinks in the dining room, where people can get up and wash their hands at a counter. We might have to retrofit our restaurants to make them easier to clean. As for tables and bar stools, those will have to be socially distanced. At my diner, I might chop up booths to make them more private.”

Another idea: Put everything outside. Some American cities, including Berkeley, California, and Cincinnati, have done just that, by announcing plans to close streets and free up outdoor dining space for restaurants.* But for many cities, wide-scale al fresco dining is unrealistic, not only because of necessary road use, but also because we can’t ask the weather to stop. There will be snow in Boston, wind in Chicago, and rain in Seattle. An open-air restaurant is a lovely thing, but ceilings were invented for a reason.

Restaurants will respond to the pandemic as they already have—by cobbling together a variety of businesses, including delivery and curbside pickup, and selling specialty groceries. Even so, their outlook is dire. Colicchio told me that more than half of American restaurants may not reopen. “In my case, for at least two of my restaurants, most of the business comes through private parties and conferences,” he said. “For the foreseeable future, that’s gone.”

3. COVID-PROOF PUBLIC ENTERTAINMENT

On the evening of Tuesday, March 10, 61 singers gathered for choir practice just north of Seattle. It was a standard rehearsal, as members sang in close quarters, shared snacks, and stacked chairs together at the end of the two-and-a-half-hour session.

Five days later, the choir director sent an urgent email to the group. Several members had developed fevers, she said. The following Tuesday’s rehearsal was canceled. But by then, it was too late. Fifty-three of the 61 singers became ill, making for an “attack rate” of 87 percent. Three members of the choir were hospitalized. Two died.

The Washington choir represents the most aggressive outbreak I have come across, with an attack rate almost twice as high as the Korean call center. It had many features we’ve already established to be dangerous: an intimate crowd gathered in a small room, sharing air, food, and surfaces. But what if singing accelerated the transmission of the disease?

In a study subsequently published in the Centers for Disease Control and Prevention’s “Morbidity and Mortality Weekly Report,” researchers emphasized that “the act of singing, itself,” might have contributed to transmission, because choir members were belting out more of the virus. Some people—known as “superemitters”—release more particles into the air when they speak, because they are unusually loud or slobbery talkers. But even normal gabbers can release an exceptional number of droplets if they’re singing or theatrically projecting their voice.

Many super-spreader events have been ceremonies that involve group prayers and exclamations, such as religious gatherings. On February 16, a 61-year-old Korean woman with COVID-19 triggered hundreds of infections when she prayed with 1,000 worshippers in a large windowless church in Daegu, South Korea. (To this day, more than 60 percent of Korea’s COVID-19 cases are in Daegu.) Two days later, in France, several hundred Christian worshippers from around the world packed into a dark auditorium in the small town of Mulhouse for an annual festival. French authorities have since linked more than 2,000 global cases to this one meeting, including cases in  French Guyana, Corsica, Burkina Faso, and Switzerland.

These stories, combined with the science of large-droplet and airborne transmission, suggest that social distancing isn’t enough: We need saliva control too. Other countries are doing so, already. Germany has reportedly banned singing at religious services, and South Korea has prohibited spitting in its professional baseball league.

Spittle rules won’t be enough to make our public entertainment places safer, either. We will need a comprehensive strategy to reduce the sort of interactions that can lead to more infections. “When we go back to sports stadiums and theaters, people are going to have to adjust their expectations,” says Joseph Allen, an assistant professor of exposure-assessment science at Harvard’s T. H. Chan School of Public Health.

First, he told me, full-capacity stadiums will be impossible in the social-distancing age, and most attendees will be advised to wear masks. Second, everything that can be made touchless should be, including ticketing and concessions. “To avoid clustering at the hot-dog stands, stadium food vendors should serve as much as possible directly to people’s seats,” Allen said. Third, public-entertainment venues will have to reimagine queuing. “Our theories about crowd control, which are dominated by concerns for physical security, typically squeeze large numbers of people into a scarce number of heavily guarded entrances,” he said. But in a pandemic, tightly packed queues are the very hazard we want to avoid. “It’ll be very important to reduce crowding at the entrance of stadiums and theaters by adding additional entrance points or staggering admissions by time to avoid overcrowding, Allen said.

When you put all of these stories, studies, blueprints, and advice together, it amounts to a relatively straightforward pandemic playbook. For memory’s sake, let’s reduce the major takeaways to a convenient acronym: SAFE.

- Social distancing: This one you probably knew before you read this article. Keep a healthy distance between yourself and others—six feet is a good general rule—especially when you are near them for an extended period of time.

- Airflow awareness: Every noncontact activity—talking, eating, working out—becomes significantly safer when you take it outside. As the previously mentioned Japanese study and Hong Kong survey indicated, the odds of transmission in a closed, indoor space are several orders of magnitude higher than in open-air environments.

- Face masks: Wear them. They’re not just for you; they’re for everybody around you.

- Expectoration (sorry for using a fancy word for spit to make the acronym work): COVID-19 appears to spread both through large-droplet transmission, such as from sneezes, and through the airborne transmission of smaller, aerosolized droplets, such as those that spray out of the mouths of talkers. Beware especially of indoor environments and activities that naturally include lots of gabbing (such as a long office meeting), singing (such as a choir practice), shouting (such as a high-school gym), or heavy breathing (such as an intense indoor workout class).

As an indoor person myself—and a lover of theater, sports, and restaurants—it’s painful to think about the range of activities that will be pinched in the next year and the businesses and lives that will suffer for it.

Toward the end of my reporting for this piece, I emailed a national-security worker who also teaches singing in the Washington, D.C., area. She’s heard that in-person singing may be off-limits until a vaccine is widely available, a possibility that would shutter musicals and vocal lessons for a year or longer. “Despite all the chaos and intense news, this has been the thing that has hit the hardest,” she said. So, she’s planning to offer singing lessons on Zoom.

America’s public spaces will have to show a similar flexibility and resiliency to make it through the next year. Even as the United States reopens, some old rituals—such as going to bars, group workouts, and packed concerts—will have to remain paused. People will still drink and sweat and sing, just differently. Eventually, the old world will come back. The great indoors will return. But until then, Americans will have to balance their rituals and nostalgia with a humble respect for our unfolding understanding of COVID-19.

* This article previously misstated that Berkeley, California, had closed its streets to make space for outdoor dining. The city has announced plans to do so, but has not yet implemented them.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.