Air pollution is no longer just Delhi's problem. From the national capital region to cities like Chennai, India's air pollution crisis is spreading across the country. Following Diwali, Delhi's Air Quality Index (AQI) surged, with several localities recording levels above 400. But the problem extends far beyond the festival or the national capital. Multiple Indian cities are now featuring among the world's most polluted urban centres.

Senior Assistant Editor K. Sunil Thomas takes a look at the growing health crisis, and the limitations of India's pollution-control measures.