By now, you've probably heard that to slow the COVID-19 pandemic, people need to adopt social distancing measures — including remaining at least 6 feet (about 1.8 meters) apart from anyone they encounter outside their homes. Where does that number come from? And how should you be applying it in your life?
The reason we need to maintain this kind of distance from each other at all is because of how easily the new coronavirus SARS-CoV-2, the microbe responsible for the illness, spreads between people. It can theoretically remain viable in aerosols for 3 hours, can be transmitted through contaminated surfaces, and it easily spreads through coughing and sneezing. The 6 feet of distance is designed to put up a roadblock to the aerosolized and droplet methods of transmission. But that standard is best understood as a reference point — not a hard line beyond which you are absolutely protected, said Krys Johnson, an epidemiologist at Temple University. And another expert told Live Science that that distance is likely not enough to be protected from the virus.
When moving around outdoors, she said, 6 feet is a good minimum distance at which to pass other people, if you can't give them a wider berth. In indoor settings (think the grocery store), she said, it's more of an "absolute minimum."
"Six feet is the average distance that respiratory droplets from a sneeze or cough travel before they settle and are no longer likely to be inhaled by other people. I have seen estimates for social distancing of up to 10 feet if someone sneezes quite hard, [or] does not cover their sneeze [or] cough," she said. "This allows those particles a little more distance to settle so that you are not breathing them in. As long as someone's not outwardly ill, though, you should be safe maintaining a 6-foot distance."
Proper social distancing, Johnson said, means not just keeping the minimum distance but thinking about how the need to maintain that distance affects others around you.
"You should indeed try to maintain this distance even when passing someone on the sidewalk. Several supermarkets have marked off 6-foot distances in their lines to ensure that people are social distancing," she said. "My recommendation is that people absolutely maintain 6-foot distance from people not in their household when at all possible. Give people a wide berth at the grocery store or pharmacy. Be cognizant of how close you are standing in line. Quickly make your shopping selections so that the next person can select theirs while maintaining social distance."
That said, according to Johnson, it may be possible in certain settings for people to interact as long as they maintain significant social distancing.
Asked by Live Science about stories of people meeting in empty parks to chat while keeping apart, Johnson said, "You should be fine six feet apart talking for an extended period of time as long as no one is outwardly ill. This distance allows any inadvertent spittle to settle to the ground before reaching the other person, reducing the likelihood of asymptomatic transmission."
Still, that's not something she'd be comfortable with in all situations, she said.
"Personally, though, I would only sit and talk for an extended period at 6 feet if I were outdoors, just for my own peace of mind," she said in an email, adding, "If someone is outwardly ill, you should ask them to isolate at home until they feel better (regardless of the ailment), and maintain 10 feet of space when asking them to do so to preserve your own health."
Not everyone is sure that the 6 foot measure is enough for non-outwardly ill, however. And there's at least some reason to be skeptical; for instance, a case of widespread transmission in a choir practice in Washington raises the question of whether SARS-CoV-2 can be spread via tiny aerosols, which can stay suspended in air for long periods. If that's the case, particles could potentially travel more than 6 feet before drying out, as Live Science previously reported.
What's more, even large droplets of mucus expelled with extreme force (as when coughing or sneezing), or carried by the wind can travel farther than 6 feet before falling, Wired.com reported.
"Six feet is probably not safe enough," Raina MacIntyre, a professor of global security and the head of the Biosecurity Program at the Kirby Institute in Australia, told Live Science in an email. "The 3-6 foot rule is based on a few studies from the 1930s and 1940s, which have since been shown to be wrong — droplets can travel further than 6 feet. Yet hospital infection control experts continue to believe this rule. It's like the flat-Earth theory — anyone who tries to discuss the actual evidence is shouted down by a chorus of believers."
So what's the takeaway? The best way to ensure your safety is to stay indoors as much as possible. Step out as needed for responsible trips to collect food and medicine, or, if possible, brief exercise in low-density outdoor spaces. Homemade masks, regular hand-washing and other steps may help reduce the risks of COVID-19 transmission if you must venture out. But the only really sure way to prevent yourself from getting infected is staying indoors and away from other people. This is true whether you're in New York, Washington or Kansas, or anywhere else in the United States.