Cities are not generally known for their cleanliness. Huge numbers of people living together in small spaces, traffic filled streets and industrial activity can all combine to create distinctly dirty urban environments. However, with often catastrophic levels of air pollution, fossil fuel energy sources and large amounts of waste, many modern cities are facing a backlash from residents and campaigners. D/SRUPTION takes a look at five cities and regions hoping to make a positive environmental change. Les mer her