Life in the city has its ups and downs, pros and cons. You get the best culture life can offer, but you also get crowded areas, very little green and a lot of pollution. The Environmental Protection Agency (EPA) says there is a much higher risk of contracting lung cancer due to air pollution if living in certain highly urban areas (see http://www.cancer.org/Cancer/news/News/epa-estimates-cancer-risk-associated-with-air-pollution and http://www.epa.gov/ttn/atw/nata2002/risksum.html for maps showing areas of higher risk).
However, all is not lost! Enormous strides are being made towards better standards of emissions and there is even a new discovered molecule called Criegee biradical or Criegee intermediate, which are powerful oxidizers of pollutants produced by combustion. These molecules not only have the ability to naturally cleaning the atmosphere, but they also form clouds as bi-product of their break-down process, helping to cool down the planet (http://www.gizmag.com/criegee-biradicals-potentially-offset-global-warming/21125/ and also Science magazine).
Also, we are just seeing the arrival of fully electric cars - dealers of CODA automotive are delivering their very first cars in Los Angeles now, March 2012. There is a bit of a race going on between EV (Electric Vehicle) manufacturers such as CODA and Tesla. Although their cars are priced slightly higher than average (mid-30 thousands and above), there are huge tax credits which can reduce the price by several thousand dollars, not including the gas savings.
Oh, by the way, did you notice something wrong with this image? ;-)