I agree that "cold hard cash" has a lot to do with this and I'm not too impressed with the IOC, but then, the IOC has never really impressed me in the past...
This being said, I would be curious to see some hard data about this pollution thing. Los Angeles and Athens are not especially "clean air" cities either, and lots of athletes were sick in Athens (I'm a bit too young to remember much about LA). Any data, anyone?