FILE - In this Nov. 10, 2017 file photo, Indian commuters wait for transport amid a thick blanket of smog on the outskirts of New Delhi, India. The petroleum coke being burned in countless factories and plants is contributing to dangerously filthy air in India, which already has many of the world's most polluted cities. India's energy-hungry industries like petcoke because it's cheaper and burns hotter than coal; they also defend their use by saying they're recycling a waste that's being produced anyway. (AP Photo/Altaf Qadri, File)