The "Smog over Los Angeles" photo is from the 1970's or 1980's. Most younger folks in the US don't realize this, but pollution here is WAY down from a few decades ago. Our air is cleaner, out rivers and lakes are cleaner. Hell, even the sides of roads are cleaner.
More to the point, people in rural areas pollute far more per person than people living in cities. We need to end rural subsidies to stop encouraging people to live in rural areas.