One of the images that impressed me most in my life was flying down the east coast of China, equivalent distance from Cape Cod to Florida, and seeing nothing but a Venus-like hellscape of smog. Wasn't any better on the ground. It was as if they had combined the worst aspects of Las Vegas development with Charles Dickens era London.
I am not at all eager to go back. I know there's lot's o' money sloshing around there, but I also don't care to spend my time in an airport smokers cage, which is basically what that place is.
I'm glad you qualified with east coast... and frankly, I agree. We live way out in the west, in what amounts to the foothills of the Himalayas, where it's pretty damn clean. I haven't been to the east coast in about ten years now, and can't imagine it has improved. The last trip I did was this one - http://pratyeka.org/ennin/ - following a Tang Dynasty Japanese Buddhist monk's diary. We got to one point where he said (at precisely the same time of year, when the weather and atmosphere was considered good and clear by modern locals) that he could see such-and-such a mountain to the west. We couldn't see shit. Visibility was, distance-wise, 10% of historical visibility.
I am not at all eager to go back. I know there's lot's o' money sloshing around there, but I also don't care to spend my time in an airport smokers cage, which is basically what that place is.