The scale of urbanisation in Asia over the past few decades has been truly astonishing and there is no sign of it stopping. In the next 20 years, another 1.1 billion people in the region will call cities their home. Sadly the rush to the bright lights is coming at a heavy cost. Many cities—especially in developing countries—are already under severe strain from environmental degradation, traffic congestion, inadequate infrastructure, and a lack of basic services, such as water supply, sanitation and waste management. Over 200 million people in Asia now live in urban slums and the number is expected to increase as cities continue to grow.  Cities have become the economic engine rooms of the region producing about 80% of Asia’s gross domestic product (GDP). But, both directly and indirectly, they are making a similar contribution to greenhouse gas emissions. The economic cost of pollution is huge. It is estimated that air pollution alone can negatively affect GDP by about 2% to 4%. Asian cities will be the main contributors to pollution costs over the next 20 years if nothing is done.

— blogs.adb.org/blog