Have a look at this article published by the CBC. Where it discusses the impact of air pollution both in China and how it having an effect on the rest of the world.
CBC News: Import air pollution from China
Photo By: Joe Dunckley
A recent article published by Scientific America discovered that if cities where to invest towards public transportation and other alternatives it could greatly reduce the amount of carbon emissions produced by urban passenger transport. In Toronto an estimated 2,838,506 tonnes of Green House Gases (GHG) are produced by passenger vehicles. The article goes in depth and analyses both the investment and savings this will create towards cities. More importantly, the article examines the massive growth of cities and the car is linked to inequality.
I highly recommend you read the article to learn more information on urban sustainability.
Photo by: Stefan Georgi