28 Aug 2020

What is a Safe Distance for Social Distancing?

A recent study by MIT (which has an excellent risk chart) questioned whether a blanket rule of 6 feet for social distancing is appropriate for activities during the COVID-19 Pandemic. This raises a number of interesting points that many have considered and it has to do with gaining knowledge of the virus and relative risk.

Over time we have learned more about the virus and how is spreads, we moved from a primarily contact based form of transmission where we focused heavily on hand washing, cleaning and disinfecting, to a recognition that the virus spread via droplets (now don’t use this to assume you don’t need to continue to wash your hands frequently, use a hand sanitizer and clean and disinfect surfaces, you still do). This led to distancing and the six foot rule and wearing of masks when close to others.

Now with more data its believed the virus is primarily spread via the air and there are additional concerns about aerosols or smaller particles that are able to float for sometime and spread much further than the larger and heavier droplets and we have more information on just how far these droplets can be spread.

This information is now leading to some questioning the six foot rule as we discover that the aerosols can travel much further dependent upon things like how loud someone was talking or singing, the amount of air flow, humidity, whether someone is in an enclosed space, etc.

All of this is actually good to know because its all about reducing risk, and as we factor in more knowledge we can develop better, and more precise mitigation strategies. Lets use this simple chart with just a few risks:

Lower RiskHigher Risk
OutdoorIndoor
Wearing a MaskNot Wearing a Mask
Few PeopleMany People
Further than 6 FeetWithin 6 Feet
Quiet Talking/SingingLoud Talking/Singing
Short time IndoorsLong time Indoors

While each of these is a relative risk with different variations in the amount of risk, lets for simplicity sake assume all of the lower risks are equal and all of the higher risks are equal and that the difference between low and high risk is to double the risk.

So we assign each low risk a value 1 and each high risk a value of 2. But some of these risk factors when put together may change the risk even more than to just to double it. Perhaps if we are indoors in a small space and people are talking loudly, that increases the risk by double the amount of counting them alone.

In that case you begin to say, hmm, maybe we should be 12 feet apart if we are indoors with a bunch of people talking loudly and should only do it for a short period of time.

This less rigid approach is how you should think about risk in your daily activities. Consider the various factors, similar to above and others and adjust accordingly; its not a one size fits all approach.

This article talks about the issue and is well worth reading for a deeper dive. In particular note their thoughts on the relative safety outdoors. That looks pretty safe and is one of the reasons, schools, gyms, restaurants and others are moving their activities there.

COVID and Social Distancing: Is 6 Feet Enough? By Kathleen Doheny

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