The thread about climate change and pollution has brought up many interesting and key points. However, there is another point about pollution that I wish to bring up (but as a different thread because it is a bit off topic).
The first thread talked about cars and climate change. However I maintain that cars are not the main culprit in global warming (assuming that it exists), but industries are. Reducing car emissions, size, and fuel usage would most likely have the immediate effect of local pollution in cities (read : less smog!) while the change made by -- more efficient -- cars would be smaller on a global scale. However, if we look at industries (including power generation) we can see that that is where the majority of the pollution comes from and many of them are not located near major cities.
Bottom line : cars should be reduced/banned/more efficient to reduce pollution in cities because there is clear proof that city pollution is mainly caused by vehicules.