New Delhi often finds itself compared to Beijing because the two capital cities share a battle against smog. For this reason, a new paper by economists Shuai Chen, Paulina Oliva and Peng Zhang on how sustained air pollution affects migration in China should be read by our city administrators, particularly in the polluted National Capital Region.

Sharp increases in air pollution in a Chinese county can halve inflows and reduce the population by 5% (because of outflows), the economists show.

An equally important detail is that highly educated citizens are most likely to respond to air pollution because they prefer to lose some income rather than bear steep health costs over their lifetime. Women are especially likely to move out or avoid moving into polluted areas to protect the health of their children.

Cities are magnets of talent. What our city governments need to realize is that the failure to improve air quality could eventually lead to the loss of human capital that sustains urban economies.