Beijing is tackling its air pollution problem; Why can't New Delhi?

The return of smog season in India's capital has again left residents asking why nothing has changed; the answer may be largely political

A decade ago, the capitals of Asia’s two largest countries both had some of the dirtiest skies in the world. On the worst days, millions were enveloped in thick gray canopies of smog that darkened the sun and besieged the lungs.

Since then, one of those cities has made significant improvements. After the Chinese government declared a war against pollution in 2013, Beijing pressed ahead with a multiyear, $100 billion effort to clean its air. The authorities clamped down on factories, forced old vehicles off the road and shifted from coal to natural gas. While more still needs to be