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It's been more than 50 years since the Clean Air Act was signed.

It was a bipartisan effort and a big success.

It is arguably one of the most successful environmental policies ever enacted in the history of our country.

It's Wednesday, November 6th, and this is Science Friday.

I'm John Dankowski. Back in the 1960s, air pollution had reached a crisis point, but then in

1970, Richard Nixon signed this landmark piece of environmental legislation, but can

this law still handle the air pollution challenges that we face today? I've been really interested

in this history for a long time because I grew up in a place that was pretty famous for once

having some of the dirtiest air in the world, Pittsburgh, Pennsylvania.

It's something that my parents and grandparents talked a lot about, but for as long as I can remember, the air in Pittsburgh's actually been pretty clean.

So to find out more about this, I called up Susan Scott Peterson.

She's a climate reporter in Pittsburgh who has been covering air quality for a while now.

Welcome back to Science Friday, Susan.

Thanks so much.

Okay, so let's start with this history and some of these stories about dirty air that my parents told.

Yeah.

So, I mean, as you mentioned, the air is a lot better now.

But I think that the fact that it used to be so bad is in part the history of the Clean Air Act.

So back in the 40s and 50s, Pittsburgh was the steel manufacturing capital of the world.

There were, as you know, steel mills and blast furnaces all up and down the riverbanks.

And then all these people who worked in the steel mills,

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