Does Covid-19 magically disappear after 1 1/2 meter?
It's math. You will be subjected to viral particles every day, everyhere, even right now in your house and job. The question is not if you get sick from a particle, but rather how many viral particles you need to have on your mucous membrane to get sick. It's called "viral load." One particle may not make you sick, because even if your defenses are not good the body can defeat a few viral particles by way of destroying a few misbehaving cells with T-Cells, also known as Leukocytes. Imagine a sick person has breathed 100000 virus particles away from his face by 10 cm. At 20 cm the number of particles has diffused by a factor of 8 (23=8). That's 12500 particles. At 30 cm the viral load is 1/27, or 3000 particles. At 40 cm it's 1/64. At 1m you get exposed to only 100 particles. At 1.5 metres you get exposed to only 29 particles. Not enough for you to get sick, even if you breathe all 29 particles... Yes?
Weelll...

As many of you are aware, I do artwork. I hesitate to call myself an "artist," because my relevant degree is an Associate of Applied Science in Commercial Art - basically a two-year, close-to-nothing, graphic arts-type piece of paper that says "yes, Bailey knows how to do pasteup, pre-1990s typography [relevant because various desktop publishing apps came out in the 80s and early 90s that made post-1990 typography little more skill-intensive than simply pressing three or four keys and messing with a mouse], 4-color process, and can draw/paint/digitize several lines in the same general area and make it look like something artistic." Anyway, I do, and have done, artwork, of many various, diverse kinds.
One of the types of artwork I have done is sprayed paint, both the spray-can variety, and airbrushing (I much prefer airbrushing, because of the inherent control one has over both the tool(s) and the medium itself).
The relevance? Welllll... In the airbrushing classrooom, things were so well-controlled pressure, workstation location, and airflow wise that one's paint droplets seldom gravitated onto anyone else's work area. The makeup of said droplets, when you get right down to it, is not that much different from a mucous droplet.
Also, notice that I did not say that one's paint droplets
never got onto anyone esle's work surface.
I said,
seldom.
In other words, every once in a while, some did. Even, occasionally, from all the way across what amounted to a full-sized studio-type classroom; something like 60 feet or more. The instructor explained that it was because some paint (he said), always drifts. Which, by the way, makes me wonder just how valid it is to say that fans in a room are effective in dispersing the droplets.
Anyway, if the wind changed, or there was a gust from the doorway, or somebody went and stood in front of the fan to cool off, or any number of things that affected the air currents in the room occurred - paint vapor suddenly started drifting in new and catastrophic directions. Not just droplets. Outright
vapor clouds.. Luckily, most of the clouds were very, very small, as we're talking about Paasche and Badger-brand airbrushes here, with little pigment cups that only held about a tablespoon of liquid at a time, and thus squirted only tiny amounts of paint if one pressed the air/[paint flow control button and moved the tool in the prescribed manner, but still.
if enough droplets to discolor a gradation on acetate can drift across a studio, seems to me it's possible for a whole lot of 'rona droplets to act in the same manner.