For the past two weeks, air pollution in the Indian capital of New Delhi has been off the scale.
A toxic mix of dust, soot from farmers burning paddy field stubble, car fumes and construction all combined into a murky grey film over the city.
The pollution was so bad visibility was reduced and the government moved to close schools and advise people to stay in doors.
While the news hit headlines, it’s still ongoing – on November 14, the government again closed schools and various initiatives have been launched to try and clean up the air.
But India isn’t alone in struggling with pollution that doctors are increasingly linking to long-term health problems.
James Haines-Young looks at why so many cities are struggling to breathe.