A group of scientists have announced that they've found some extremely old pollution this week, picked up in an ice cap in the Peruvian Andes. Traces of air pollution, they suggest, date back to over 400 year-old mining operations that happened hundreds of miles away. Researchers suggest that this is the first clear evidence of human-made air pollution in South America from any time before the Industrial Revolution. Pollution here likely originated in what's now Bolivia - in the Potosí mountaintop silver mines.
The city of Potosí has a rich industrial history - so rich, in fact, that the area is designated a UNESCO World Heritage site. Back in colonial times, Potosí became the largest silver mining source in the world.