I am reading Rubicon by Tom Holland(?) and he mentions a traveler seeing the smog from Rome before the city, and publicani working thousands of slaves to death over the pockedmarked landscape of Spain, covered in smog from smelting furnaces, belching fumes that killed birds and burned the skin and turned it white. He says that smog sprang up wherever the Romans power spread. Do we know if this industrialization affected the earth at all from the sources and the sciences? Thank you.