This is scientific Americans 60 second science. I'm Karen Hoffman. This will just take a minute.

When you think about air pollution, you may picture smoke stacks belching out noxious black clouds or the gas-guzzling

SUVs crowding the highways, but different cultures found different ways to foul the

atmosphere long before the Industrial Revolution. The latest example of

pre-industrial pollution comes from Peru almost half a millennium ago. To get a

read on what humans have been ejecting into the air, researchers pulled ice cores from

Calchaya, a glacier high in the Andes. The samples provide an annual archive of

elements that have been circulating in the atmosphere stretching back to the year 793.

Analyzing the core, the researchers found that prior to about 1532, the ice harbored

only a sprinkling of dust and ash, remnants of the occasional volcanic eruption.

But at about the 1540 mark, corresponding with the start of colonial mining and metallurgy,

the cores suddenly contain chromium, molybdenum, antimony, and lead.

The finding is in the proceedings of the National Academy of Sciences.

Of course, these waste products are a proverbial drop in the bucket compared to the toxins

we put out today today because we've developed

ways to pollute that people back then could only have dreamed of.

Thanks for the minute. For Scientific Americans 60 Second Science I'm

Karen Hopkins.