Spread of droplets in the air vs. distance

[Beliavsky]

To reduce the transmission of coronavirus, people are recommended to stay 6 feet apart from others. The 6 feet number is a simple guideline, but there is not much difference between 5.9 and 6.0 feet.

How does the number of droplets you breathe from another person vary with the distance d? Is it 1/d, 1/d^2, or something else?

 

[FactChecker]

There is a lot of COVID-19 related discussion of this. The size of the droplet is critical. Smaller droplets are more likely to stay in the air, go farther, and drift with air currents. If there is a mixture of droplet sizes, it would effect the amount you would breathe at specified distances.

This looks like a good reference to get started: "Aerosols, Droplets, and Airborne Spread: Everything you could possibly want to know" by Justin Morgenstern

 

[Jarvis323]

A group of several hundred scientists just published an open letter, "It's time to talk about airborne transmission of covid-19". They criticize out of touch health authorities and summarize the body of knowledge about airborne transmission. I think it's a good starting point for answering your questions.

https://academic.oup.com/cid/article/doi/10.1093/cid/ciaa939/5867798