Nature Geoscience, 2 February 2017
Beijing may be the poster child for air pollution, but Delhi, where air pollution causes up to 30,000 premature deaths annually, has earned the dubious distinction of being the most polluted megacity in the world1. Late last year, Delhi's already bad air quality became worse. Emissions from coal-fired power plants or vehicles were not responsible; instead it was fireworks set off to celebrate the annual Hindu festival of Diwali. The Diwali fireworks are known to cause large increases in particulate matter and metal in the atmosphere2, 3.