EDIT: apparently my post below was predicated on a false assumption, please disregard.

That's Beijing, not Shanghai, and I think we can assume that Beijing is at least slightly cleaner than Shanghai, if not by much.

According this article[0], Shanghai's level reached 602.5, which, when compared to the data on the graph you linked, is about 75 points higher than Beijing.

[0]: http://abcnews.go.com/International/wireStory/smog-extremely...

Beijing sits in a geographic bowl (trapping pollution) and is inland from the coast compared to Shanghai. It also gets hit with dust storms from the desert to its west, all of which lead to it being "crazy bad"[0] in relation to Shanghai.

re: "crazy bad" being tweeted by the US Embassy in Beijing -- a cautionary tale on string sanitization. "The "crazy bad" terminology – which was at odds with the normally sober and scientific language of the Twitter account – appeared to have been a joke embedded in the embassy's monitoring program and triggered by a reading that was off the normal scale."

[0] http://www.theguardian.com/environment/blog/2010/nov/19/craz...

According to the data from this page: http://kopf.github.io/chineseair/ Beijing seems to typically have higher pollution levels than Shanghai.

Beijing is generally worse more often, partly because they get hit by dust carried from the increasingly large Gobi Desert in addition to all the man-made pollution.

Not really. Beijing definitely get dust, but the real problem is that Beijing is trapped in a bowl and gets some wicked inversions. And to think I could see the summer palace from my office just yesterday.