Edited by Paolo Pascual. Filmed by Jyotsna Singh. Additional footage from Reuters.
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Toxic pollution in New Delhi has sparked a public health emergency. On the air quality index levels of harmful particulate matter shot off the scale.
We spoke to four residents to see how it affects daily life.
India is home to seven of the 10 most polluted cities on the planet.
In Delhi, the smog is worst in winter after Diwali, the Hindu festival of lights.
This year, people have been told to stay indoors. Schools have shut. Construction has been stopped.
At least 140m people in India are breathing air 10 times more polluted than the level deemed safe by the World Health Organization. This pollution is linked to heart attacks and strokes, asthma, and stunted development.