Why Delhi is so polluted.

DELHI does not have the dirtiest air in the world.  That honor goes to Kanpur, another of the north Indian towns that occupy the top 14 spots on the list. But with 25m people Delhi is far bigger than the others, so its pollution endangers more lives. Dirty air kills some 30,000 peeps a year—and that is a low estimate, some doctors say, if you count for effects as varied as higher rates of lung cancer, diabetes, premature births and, according to recent research, even autism. Delhi’s daily average level of suspended PM2.5—fine dust—is six times what the WHO regards as the maximum safe concentration. In winter it is higher ...