Here was the typical view out my window in Beijing through the first half of 2008, leading up to the Olympics, as highlighted maybe a million times on this site:
This picture thanks to reader Robert Bott, who sends a link to an LA Times archive of "smog in LA" pictures that show how the Southland looked before the big cleanup of roughly the 1970s onward.
The fumy shot above is before my time, but I certainly remember conditions sort of like it in the 1960s. For instance, one high school tennis tournament in Pomona when it seemed hard even to see across the net (the serves came out of nowhere) and it burned your throat simply to breathe.
Why is this good news for Beijing? Well, because it shows that in fact things can be cleaned up. This is the same lesson as taught by the improvement in London air quality from Dickens's time to now, or in Chicago's environment, or Tokyo's. And why is it not so consoling? Because it took decades for LA and California -- and they were already rich when they were starting. They also were not just on the cusp, as Beijing and the rest of China are, of a huge boom in automobile ownership and the movement of the peasantry into mechanized urban life. So maybe the proper sentiment is not so much "good news" as "good luck!" -- as explained during the Olympic year here.