All but one of the world’s top 20 most polluted cities last year were in Asia, a new study shows. The majority of these cities – 13 – are in the world’s most populous country, India, where booming economic growth is fired largely by coal and where hundreds of millions live in traffic-clogged and congested megacities .

Thirteen of the world's twenty most polluted cities are in India, with Byrnihat being the most polluted globally. Delhi remains the most polluted capi