India is home to seven of the world’s 10 most polluted cities, Bloomberg reports, citing a study by IQAir AirVisual and Greenpeace. Gurugram was the world's most polluted city in 2018 with an average air quality index of 135.8, followed by Ghaziabad (second globally), Faridabad (fourth) and Bhiwadi (fifth). But the smoggy air isn’t limited to the usual suspects – as many as 22 Indian towns, including several populous ones in the northern plains, feature among the world’s 30 filthiest cities. Pollution-related healthcare costs and productivity losses cost India nearly a twelfth of its GDP, according to the World Bank. Here's what people are saying.