Nobody knows for sure but I'm addicted to news and remember this well. A bigshot at CDC was working out the guidelines at home and his 14 yo daughter doing homework they started talking about science. He asked her what might be a safe distance in school...3 feet.....5 feet.....10 feet? And she said 6 feet not too close and not too far. He liked the answer and went with it.
I remember telling this story back then and of course nobody believed me....but then too nobody believed me about lockdowns either.
Nope most of the people running the world and your cities and countries are satan worshippers. They have rituals and in those rituals they all wear masks and stand 6 feet apart. That is where it came from.