India, Jan. 8 -- At some point in the last couple of years, buying an air purifier stopped feeling like a luxury and started feeling like basic maintenance. Now we check the Air Quality Index the way our parents perhaps once checked the weather, sometimes curiously, mostly anxiously. "Bad air today," I text my sister. "Take a cab, not an auto." We commiserate over the added cost of clean air, the added cost of life itself.

Coughing fits left me vomiting after work last winter; just a month ago, a cab ride to a theatre festival felt like breathing a smoked chimney. Masked and silent, those of us in the car seemed to share the same fear about Delhi's future. I retched quietly, my heart drumming fast, distracting myself with social media as...