We hear a lot about pollution and particularly what we are doing to the atmosphere. It seems we have been doing it for a very long time. Ice core samples from Greenland show raised levels of lead in the atmosphere beginning around 500BC. This is the earliest evidence of anthropogenic (human-caused) pollution. It was produced by the people of Ancient Greece and Rome using lead to make water pipes and tanks, smelting the metal to extract it from ore and then shape it.