Mask Up and Shut Up

COVID-19 transmission would go down if we spoke less, or less loudly, in public spaces. Why aren’t more people saying so?

COVID-19 researchers have rightly extolled the virtues of masks, hailed the necessity of ventilation, and praised the salutary nature of outdoor activities. But another behavioral tactic hasn’t received enough attention, in part because it makes itself known by its absence. That tactic is silence.

Yes, it is finally time to talk, in this pandemic, about the importance of not talking in this pandemic.

“Every route of viral transmission would go down if we talked less, or talked less loudly, in public spaces,” Jose L. Jimenez, a professor at the University of Colorado at Boulder, who studies disease transmission, told me. “This is just a very clear fact. It’s not controversial.”

Silence is golden as an antiviral strategy because of how this disease spreads. The coronavirus seems to move primarily through viral particles that erupt from our faces when we sneeze, cough, talk, or sing. Some of these particles are heavy enough to splash on a nearby surface or fall quickly to the ground. Those are called large droplets. They are large only in comparison with the smaller globs that spray from our mouths and linger in the air in a swirling particle cloud. These are called aerosols.

Viral particles hitch a ride out of our bodies on these droplets and aerosols. They travel through the air—droplets, for a few seconds; aerosols, for several minutes—and can lodge in the noses, throats, and lungs of other people. Thus conveyed by the free transit of our exhalations, the virus travels to a new host.

The goal of COVID-19 public-health guidance is to shut down this viral transit system: Good ventilation disperses aerosol clouds; distancing reduces other people’s vulnerability to these particles; masks block them from our mouths and noses.

But what if we tried to limit the production of these virus-laden particles before they even left our bodies? That’s where volume control comes in.

Talking less, more quietly, or not at all limits the manufacture of both large droplets and aerosols. When you breathe or whisper, your respiratory system doesn’t emit large droplets. Jimenez told me that, compared with yelling, quiet talking reduces aerosols by a factor of five; being completely silent reduces them by a factor of about 50. That means talking quietly, rather than yelling, reduces the risk of viral transmission by a degree comparable to properly wearing a mask.

“The truth is that if everybody stopped talking for a month or two, the pandemic would probably die off,” Jimenez said. While still emphasizing the importance of distancing, he elaborated that without any close-contact communication, it would be difficult for this virus to continue moving between people. (It’s unadvisable to test the most extreme version of this thesis by forming a silent mosh pit, or spitting in every direction when you walk down the street.)

Jimenez is not the only scientist banging the drums on Shut-Up Island. Others agree that a little bit of speech policing could go a long way to reducing viral transmission. Donald K. Milton, a professor at the University of Maryland School of Public Health, who has studied how surgical face masks can reduce viral spread, told me in an email that “silence and quiet speaking are reasonable means of intervening” to reduce COVID-19 transmission.

One of the more curious international success stories of the pandemic is Japan. While much of the world emphasized the importance of testing and tracing, Japan initially had no mass testing and no sophisticated means of contract tracing. Yet, adjusted for population, the country currently has approximately 98 percent fewer COVID-19 deaths than the United States. Much credit has gone to its crystal-clear public guidance to avoid the three C’s: closed spaces, crowded places, and close-contact settings, including “close-range conversations.”

That third C deserves more amplification. Even after its transit ridership bounced back to normal, Japan reported no outbreaks on Tokyo’s famously crowded subways. The city’s trains are typically well ventilated, and Japanese people have had decades of practice wearing masks. But something else is at work here: Japanese commuters have an informal rule to avoid talking loudly on trains, if at all.

So while New York City spends $15 million a month blasting its subways with antimicrobial sprays, the Japanese keep their trains safe with a cheaper tactic: masking up and shutting up.

If Americans imported Japan’s subway rules to our public life, we might be able to accelerate our return to a more muted form of normalcy. Several times in the past few weeks, I’ve heard people talking loudly on their cellphones in grocery stores and pharmacies, sometimes with their masks pushed aside from their mouths to improve the clarity of their diction. Such behavior displays a total failure to understand how the disease spreads.

Here’s one solution: Library rules for America. Every time you walked into a school, a medical clinic, a drug store, a barbershop, an office, an airplane, a train, or a government building, you should see a sign that read: Hush for Your Health; or Make Good Choices, Lower Your Voices!; or Keep Quiet and Carry On. “In terms of the science, I am convinced that something like this library rule would reduce all modes of viral transmission,” Jimenez told me.

Signs and guidance can only do so much. The backlash to masks among some Americans—mostly conservative men—suggests that a certain segment of the population might rebel against library rules by, say, filming videos of themselves purposefully yelling into a barista’s face.

“What we’ve learned from the mask experience is that many Americans don’t like being told what to do if they don’t understand why it’s necessary,” Jimenez said. “People need to understand that this virus is in the air, and that they breathe out 10 times more virus when they are shouting or speaking loudly.”

Most Americans aren’t used to thinking about any auditory dimension of this pandemic. For example, online shame-mongers often post pictures of ostensibly crowded beaches. These snapshots don’t capture several important factors, such as how long people are standing right next to one another. Crucially, they don’t tell us anything about sound. Are those sunbathers under a big umbrella shouting at each other about beach decorum, or quietly immersed in a book? In a plague spread commonly through the air, the soundscape of our interactions is as important as the photo image of our behavior.

A superior focus on exhalation science and aerosols might help people understand what environments are surprisingly safe, or surprisingly risky. In many cities, restaurants have recovered faster than movie theaters. But movie theaters with spaced-out seating, universal mask wearing, and complete silence might be less risky than indoor restaurants, where diners are talking and chewing without masks. “I can’t name a movie-theater outbreak in the contact-tracing literature,” Jimenez said, while also stressing that movie theaters cannot be considered risk-free, given that they are poorly ventilated indoor spaces where people spend several consecutive hours. “I can tell you that theaters don’t seem nearly as dangerous as a loud restaurant or bar, where people have to speak loudly to be heard.”

Gyms, by contrast, might seem safe if everybody is working out in reverent silence. But one study of exhalation flows by researchers at the University of Cassino and Southern Lazio in Italy estimated that most people expel more viral particles while breathing during heavy workouts than they do standing and speaking. Talking normally after a heavy workout could expel as many viral particles as shouting while standing at rest. These estimates are rough and differ from person to person. But the clear takeaway is that huffing-and-puffing on a stationary bike in a crowded room is risky, even if you never say a word.

Exhalation mitigation can’t be considered in a vacuum. It’s part of a holistic approach to stamping out the virus while cautiously resuming the activities that bring joy, meaning, and community (and, yes, consumer revenue) to our neighborhoods and cities.

The best way to keep people safe from COVID-19 is to understand the full story of viral transmission and reverse engineer a barrier for every step in the process. Imagine, Kurt Vonnegut–style, a bullet of viral transmission traveling backwards in time out of its newly infected host. The virus-soaked aerosol dislodges from the patient’s lungs or nasal cavity. It magically travels out through their nose, into the air, where it lingers for several minutes, before being inhaled by a man, without a mask, who is yelling backward gibberish in a crowd.

We can intervene at every stage in this story, with masks to block the virus, social distancing to separate the crowd, and ventilation to disperse the aerosols. But why would we ignore the founding event, which is the minting of the viral bullet? Spare your voice; save a life.