[throwup238]

> Settlements used to be covered in smog due to coal fires for example.

London first tried to ban burning coal within the city in 1306 due to the air quality.

[ricardo81]

That long ago. Surely that helped identify it as a problem even though the science behind it would have been lacking.

[jl6]

I strongly suspect that most of the things we now know to be problematic were also known to be problematic to the ancients, but were thought still to be worth it for their rewards. That’s pretty much where we still are today. Nobody likes breathing pollution, everybody likes modernity.

[JKCalhoun]

I suppose even then it would have been obvious to anyone traveling outside London that, hmmm, the fog/smog goes away out here. Only in major cities… What could it be?