Social Distancing Is a Lot More Complicated Than Staying 6 Feet Apart

People exercising in an outdoor class on August 24, 2020 in Islip, New York.
People exercising in an outdoor class on August 24, 2020 in Islip, New York.
Photo: Al Bello (Getty Images)

The 6-foot rule for distancing from others during the covid-19 pandemic might be too rigid for its own good, a group of experts in the U.S. and UK are arguing. In a new paper out Tuesday, they make the case for adopting a more nuanced approach to staying safe, where people take into account things like whether they’re indoors or outdoors, staying in a location for a prolonged time, or wearing a face mask in order to figure out their risk level and how far apart they should be from others.

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The crux of their argument, published in the BMJ on Tuesday, is that the 6-foot rule—or 2-meter rule, outside of the U.S.—endorsed by public health groups like the World Health Organization is based on antiquated science first collected more than half a century ago, usually involving viruses very different from the culprit behind covid-19, the coronavirus called SARS-CoV-2. The group of experts include Nicholas Jones, a primary care doctor and doctoral research fellow at the University of Oxford in the UK, Zeshan Qureshi, a UK pediatrician, and Lydia Bourouiba, a mathematician and associate professor at MIT who has studied the fluid dynamics of how infectious diseases spread, including those caused by respiratory viruses like SARS-CoV-2.

As the authors note, we’ve had to learn and relearn a lot about how SARS-CoV-2 works. Initially, for instance, it was thought that the coronavirus was difficult to transmit between people at all. Even once human-to-human transmission was confirmed, it was still assumed that the virus was mostly spread through close contact with large droplets emitted by infected people and that these droplets had a very short range before they fall to the ground, roughly extending to 6 feet.

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In recent months, however, studies have shown that the virus can stay intact in tinier aerosols, which are capable of traveling farther than 6 feet and can stay aloft for longer periods of time. Other evidence has suggested that both droplets and aerosols can be propelled farther than 6 feet under the right conditions, such as indoor places with strong airflow from an air conditioning system.

Though there are still questions about how much of a role aerosols play in driving transmission of the virus, evidence continues to accumulate that covid-19 can at least sometimes act like an airborne disease. And as such, the authors argue, it’s time to retire and replace the 6-foot rule.

Rather than think exclusively about personal space, they say, people should consider their circumstances. If you’re outdoors and wearing a mask, then the risk of transmission during a group activity with only a few people should be relatively low and the need for distancing is less stringent, even if you’re there for a while. If you’re indoors in a well-ventilated place, not wearing a covering, and around people who are talking, that risk climbs, and distancing matters more. And if you’re indoors for a long time, not wearing a face covering, and around people who are yelling or singing in a poorly ventilated room, that’s a much higher risk than the first scenario, and ideally you shouldn’t be there at all; but if you are, then keeping a distance is especially important, though it may not be sufficient to prevent you from becoming infected.

It’s admittedly not as easy to crunch down into a one-sentence heuristic as the 6-foot rule, though the authors have created a handy graphic. But the nuance of this advice might make life more comfortable for people earnestly worried about walking in the park or doing other outdoor activities, they argue.

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An example of how people should evaluate their risk of getting covid-19 in a group setting, according to the authors. Importantly, this model only accounts for the relative risk of being around infected people with no visible symptoms.
An example of how people should evaluate their risk of getting covid-19 in a group setting, according to the authors. Importantly, this model only accounts for the relative risk of being around infected people with no visible symptoms.
Graphic: Jones, et al/the BMJ

“This would provide greater protection in the highest risk settings but also greater freedom in lower risk settings, potentially enabling a return towards normality in some aspects of social and economic life,” the authors wrote.

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Of course, keeping a flexible distance isn’t the only thing we can do to keep ourselves safe as possible during this pandemic. It’s important to wear a face mask when indoors with people outside of your household and outdoors when distancing isn’t possible. Hand-washing and sanitizing also remain important. Businesses need to keep their spaces clean and provide good air ventilation, while hospitals and other high-risk places have to keep their workers safe with ample personal protective equipment.

Science writer at Gizmodo and pug aficionado elsewhere

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DISCUSSION

such as indoor places with strong airflow from an air conditioning system.


The chart seems contradictory or I’m not understanding it (highly likely). It would seem to me in a poorly ventilated space the chance of the virus being spread through the air would be less likely assuming you are a reasonable distance away from the infected person. In an area with better ventilation, ie the wind blowing or the AC running, it seems like the virus might be carried further than the typical 6 feet we’ve all been taught.

It seems to me proximity and duration are the key factors. Wearing a mask next to an infected person will help somewhat but if you stay there long enough and that person is talking or singing next to you that mask probably won’t be a significant deterrent from inhaling virus particles. I’m just not seeing the big difference in indoors and outdoors, especially when in close proximity for an extended period of time.