Arvind Kejriwal

When Kejriwal unveiled a blueprint to tackle the smog in New Delhi—called the world’s most polluted city by the World Health Organization—many were skeptical. A key component: an “odd-even” pilot project in which vehicles were allowed on the roads only on alternate days. The uplifting result of the pilot this January: Roads were less clogged, hourly particulate air pollution concentrations dropped by 13%, and citizens could breathe deep.