The post-monsoon period in Delhi has become a time of smog. In November, the city’s pollution index reached its highest levels, classified as “severe plus”, cloaking the city in thick, brown smog and forcing schools and offices to close.
Prof Andre Prévôt, of the Paul Scherrer Institute, who led a group of scientists investigating the causes, said: “The visibility drops drastically – often to just a few hundred metres – and it feels as if standing in a heavy soup of pollution.
