A thick, gray pall of smog settled over India’s capital in recent days, prompting the government to ban millions of private vehicles from the streets on Monday, a day after the city recorded its worst air quality in three years. Delhi is the most polluted major metropolis in the world, a condition that intensifies every year starting in October as temperatures cool and wind speeds drop. The pungent-smelling air makes eyes water and can induce coughing and breathlessness even for those without respiratory illnesses. Last week, the city declared a public health emergency, and schools have been shut down. The smog is a cocktail of vehicular emissions, industrial pollution, construction dust and crop burning in neighboring states. Efforts by local and federal agencies to combat the annual scourge have done little to bring relief to the capital: On Sunday, Delhi recorded its worst overall air quality […]