Should we expect less pollution with a larger population?

“Air quality in the US is getting worse and could be killing thousands, study finds” (CNN).

The implication of the article is that, given sufficiently aggressive government regulation, we should expect improved air quality every year.

But if we combine a growing population (chart) with a trend toward greater urbanization (data), wouldn’t our starting assumption about air quality be that the typical American would be breathing filthier air every year? If we hit any kind of technological plateau, a larger denser population should experience dirtier air, no?

We are gradually adopting some cleaner technology, but we are also gradually growing in number of people and density. Why is CNN shocked that one growth curve can’t beat the other consistently?