Every year as winter descends, Delhi’s air thickens into an opaque, toxic fog.

People are reduced to coughing fits. Throats burn. As do eyes. Chests feel heavy and breathing is laboured.

“It’s dystopian. The air smells burnt all the time,” said Piya Srinivasan, an academic who moved to the Indian capital for work two years ago. “Instinctively you want to cover your nose.’’

The city’s pollution this time of year is notorious. It’s the equivalent to smoking anywhere from 33 to 50 cigarettes a day. Schools and offices close. Coal plants shutdown. Residents stay indoors. Cricketers vomit during matches. Pets are put on ventilators. The sun is a rumour floating somewhere above the horizon.

And people die.

Air pollution is shortening the life expectancy of Delhi residents by about 12 years according to a September report by the Air Quality Life Index at the Energy Policy Institute at the University of Chicago.  Another study, by the Institute for Health Metrics and Evaluation, found one in seven deaths in Delhi in 2023 was linked to polluted air, claiming more lives than high blood pressure, diabetes or obesity related disease.

Delhi’s Air Quality Index (AQI) measures pollutants, including the level of fine particulate matter PM2.5 that can clog lungs, on a scale of 0 (clean) to 500 (maximum pollution).

Since the beginning of November, the index has been hovering between 300 and 400. This is more than 20 times the limit recommended by the World Health Organization.