I have roughly two use cases in mind here: 

a) the sort of person who wasn't that trustworthy in the first place and was probably going to start hanging out with friends within a few weeks even if official quarantines weren't lifted, but who might follow basic precautions if they were spelled out clearly.

b) small high trust networks where everyone has been quarantining (and documenting their quarantine), nobody has been interacting with anyone outside the network, etc. (but, still with a margin of error added so that a single person who's been exposed unknowingly doesn't end up auto-infecting everyone)

[ Parent Question — LessWrong Coronavirus Agenda ]

What is the safe in-person distance for COVID-19?

by Raemon 1 min read26th Mar 202015 comments


I'm not sure where the 6' number comes from, and I'm skeptical it really holds up as something I'd be comfortable maintaining for an extended period of time (If someone with c19 coughed at me from 6' away I would not feel very safe). I'm guessing the 6' is more like a quick rule for people who are only interacting briefly.

How much does it matter whether you're up/downwind? I've heard conflicting things about how airborne it might be.

I'm interested in this largely for "Okay, assuming we need to be careful about this for months at a time, what sort of practices could we use to maintain in-person social ties, indefinitely, without risk?" (i.e. going on long walks, visiting each other's house where 1-2 people hang out in the street or sidewalk and house denizens hang out on the porch, etc)

I'm guessing this has separate answers for "outdoor" and "indoor." 

Current Answers:

  • Indoors: Basically it's not safe.
  • Outdoors: 10 meters (30 feet) seems safe, if nobody is upwind/downwind of each other. But I'm unclear what the falloff range is.
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Another reference (being reported in the news): Turbulent Gas Clouds and Respiratory Pathogen Emissions - Potential Implications for Reducing Transmission of COVID-19

Given various combinations of an individual patient’s physiology and environmental conditions, such as humidity and temperature, the gas cloud and its payload of pathogen-bearing droplets of all sizes can travel 23 to 27 feet (7-8 m). [...] Eventually the cloud and its droplet payload lose momentum and coherence, and the remaining droplets within the cloud evaporate, producing residues or droplet nuclei that may stay suspended in the air for hours, following airflow patterns imposed by ventilation or climate-control systems.

So indoors basically no distance is safe, outdoors maybe 10 meters is safe if people aren't up/down wind of each other.

From "A choir group had 60 people show up for practice. Now 45 are sick.":

Ruth Backlund, a co-president at the Skagit Valley Chorale, said the group was monitoring public health guidelines at the time of the practice and had asked people to stay home if they showed even minor signs of illness. The group gathered in rows facing a piano and a choir director. They were all in individual chairs and had space to keep separated. Ms. Backlund had made sure there were extra soap dispensers in the bathrooms for people to wash their hands.

“Nobody was sick. Nobody touched anybody. Nobody shook hands. Nobody hugged everybody like you might do in a group. There was none of that,” Ms. Backlund said.

Given that they were spaced out and 1 asymptomatic person probably infected all 45 out of 60 in what must be a reasonably large room, it seems just impractical to keep sufficient distance to be safe indoors.

You might try this article and the many references therein. Sorry I don't have time for a better answer at the moment :-)

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