Smog envelops the Jama Masjid Mosque in the old quarters of New Delhi, which has the world's most polluted air that worsens in winter. AFP 
Smog envelops the Jama Masjid Mosque in the old quarters of New Delhi, which has the world's most polluted air that worsens in winter. AFP 

Why India's poor air quality is taking a toll on its economy