From Lahore and Delhi to Hanoi and Guangzhou, the most polluted cities on earth are in the 85 world. On this episode, we consider how the problem of pollution looms over the world's fastest-growing places, damaging both public health and economic development.

First, journalist Pia Heikkila (@piaheikkila) reports from Delhi, where consistently hazardous levels of smog have given rise to a new anti-pollution industry. Then, we talk with Urvashi Narain, a senior environmental economist at the World Bank, about the economic and social cost of pollution, and what governments around the world are doing about it.