Six feet might not be enough to protect you. Here’s why.

When you hear the phrase “social distancing,” is the first thing you think “six feet apart?”

If so, that’s completely understandable. We’ve heard about the importance of staying 6 feet away from people to prevent the transmission of SARS-CoV-2, the novel coronavirus that causes COVID-19.

It makes sense, since close contact with an individual who has a virus is very often how viruses spread. 

And that, for the most part, seems to be true with this coronavirus. 

Two different studies from China found that people living under the same roof as a person with the disease were more likely to get the virus than other close contacts who weren’t under the same roof.

But that doesn’t (at all) mean that you’re safe as long as no one in your household has the virus. 

In fact, while 6 feet is a safe distance to keep between yourself and someone walking on the street, a plethora of evidence suggests that indoors — like in a grocery store — 6 feet might not be enough to protect you. 

The CDC and WHO maintain that SARS-CoV-2 is transmitted largely via droplet transmission. Droplet transmission occurs when a person with the virus sneezes, coughs, or otherwise expels large particles containing the virus, and another person is close enough to come into contact with those droplets. 

Hence, the 6 feet rule. 

However, there’s evidence — especially with sneezes — that large droplets can travel farther than 6 feet. 

A study published in JAMA Insights found that the cloud of particles emitted from a sneeze can “span approximately 23–27 feet.”

A sneeze can release about 40,000 droplets, and a sneeze or cough can send about 100,000 contagious germs in the air at upwards of 100 miles an hour (yes, really).

This is why masks are so important.

Cloth masks likely aren’t going to stop every viral particle from getting into the outside world, but they help — especially for larger particles. 

Other particles emitted — sometimes as part of a sneeze-cloud, but other times from any exhalation of breath — can be so small they don’t immediately fall to the ground, but linger in the air

(A letter published in the New England Journal of Medicine reported that SARS-CoV-2 can linger in the air for up to 3 hours. While the aerosols in the experiment were created artificially, some other studies have found similar results.) 

This makes sense if you think about cooking oil, hairspray, and perfume — all aerosolized particles you can sometimes smell long after the spray has left the bottle. 

In addition to staying in the air longer, these smaller particles can travel further than large droplets, as depicted in this figure. Those small, further traveling particles can have a big impact. 

That impact is illustrated well by what happened when a choir in Washington held a rehearsal in a room the size of a volleyball court. They avoided close contact, forgoing the usual hugs and handshakes. 

But because of the forceful exhalation of breath from all that singing, one asymptomatic person who didn’t realize they had COVID-19 released many small viral particles into the room. The enclosed space trapped those particles for the duration of the 2 1/2 hour choir practice. 

Over 4 days, 45 of the 61 singers developed symptoms of COVID-19. With 60 people in a room the size of a volleyball court, some of the singers were definitely 6 feet away from the only person with the virus.

So if the choir did everything right, why did so many people get sick? 

It was sort of a perfect storm for infection, according to Dr. Erin Bromage, who teaches courses in immunology and infectious disease at the University of Massachusetts Dartmouth.

The 6 feet away guideline is primarily effective either when outdoors or only indoors for a short period of time. This is because of something called “viral load,” which means the amount of virus a person is exposed to. 

Think back to the perfume analogy. If you’re quickly passing through a room where perfume has just been sprayed, you might only get a whiff of the scent. But if you’re in the room for a while, you’re taking in perfumey breath after perfumey breath. 

When we’re talking about a virus and not perfume, a certain amount will cause a person to get sick. The higher the viral load, the likelier it is a person will become sick. 

This is why so many frontline healthcare workers are getting sick — they’re not just passing people on the street or in the grocery store, they’re spending all day in rooms with patients and breathing in very high viral loads. 

I know the idea of tiny viral particles floating in the air is scary, as is the idea that a distance of 6 feet isn’t always enough to protect yourself. 

But it’s important to remember that the real danger is prolonged exposure in enclosed spaces.

In a blog post, Bromage puts it this way:

“When assessing the risk of infection (via respiration) at the grocery store or mall, you need to consider the volume of the air space (very large), the number of people (restricted), how long people are spending in the store (workers — all day; customers — an hour). Taken together, for a person shopping: the low density, high air volume of the store, along with the restricted time you spend in the store, means that the opportunity to receive an infectious dose is low. But, for the store worker, the extended time they spend in the store provides a greater opportunity to receive the infectious dose and therefore the job becomes more risky.”

Healthline

To recap: 6 feet away is probably sufficient protection for outdoor exposure or brief indoor exposure. 

But sitting in a room with someone who has the virus for even an hour isn’t a great idea unless you have the protection of something like an N95 mask. 

This is why it’s extremely important to save those masks for people who, in providing the essential services we all depend on, must spend their days in those enclosed spaces. 


Katie MacBride is a freelance writer and editor. In addition to Healthline, you can find her work in Vice, Rolling Stone, The Daily Beast, and Playboy, among other outlets. She currently spends far too much time on Twitter, where you can follow her at @msmacb.