If this Moment of Science were a fairy tale, it might begin, "Once upon a time there was air pollution." Not because there is no longer air pollution, but because we usually think of industrial air pollution as being a fairly recent problem.
Beginning perhaps with the industrial revolution. However, research has indicated that wide-spread industrial air pollution goes at least as far back as the ancient Greeks and Romans.
A Long History
Environmental scientist Ingemar Renberg sampled sediments from beneath nineteen Swedish lakes. He discovered that naturally occurring lead concentrations remained fairly constant for many centuries after the lakes were formed about ten- thousand years ago.
Lead In The Air
Then, about twenty-six hundred years ago the lead levels in the lakes began to rise. This was when the Greeks began minting silver coins. The silver for the coins was extracted from ore that also contained lead, and the smelting process released lead into the air.
The ancient contamination recorded in the lake sediments increased again about two-thousand years ago, when the Romans were smelting lead throughout south and central Europe, releasing even more lead into the air. As the Roman Empire declined so did the lead levels in the Swedish lakes.
Then about 1000 A.D. the lead levels in the lakes began to rise again. At this time the Germans had begun to mine silver and lead. By the beginning of the 19th century the lead measured in the lakes was as much as 3.5 times what it had been during Roman times.
Apparently some of the lead that escaped into the air during these ancient times reached Sweden, since the levels of lead in the lakes correspond with the lead processing activities in south and central Europe.
While industrial air pollution is certainly not good, Renberg's research has shown that it's far from new.