Delhi led the ranking of major polluted cities on October 28, 2019, a day after celebrating a Diwali that officials had hoped would mark a green beginning.

A court in 2018 banned all fireworks apart from “green crackers”, fireworks that produce less emissions because they have a different chemical composition.

However, in late October of 2019, Delhi air quality and Kolkata air quality rose sharply to beyond index levels. Delhi saw PM2.5 levels of up to 829.2 micrograms per cubic meter (ug/m³) and a U.S. Air Quality Index of 1005. The U.S. index only goes as far as 500.

At the same time, Kolkata had PM2.5 levels of 633.4 ug/m³ and an AQI of 621.

Delhi most polluted

Delhi leads IQAir AirVisual’s pollution ranking of major global cities

India’s science and technology minister announced earlier in October that government scientists had developed green crackers that emit 30 percent less pollution and were quieter.¹

However, sellers reported limited stock and that buyers were confused as to what to buy. A lot of the green stock had been shipped before the government agreed to the idea of a QR code to identify genuine green crackers.²

Reports said that conventional fireworks were still in use this year, and that there were complaints of fireworks being set off outside the legal two-hour window.³
The weather also played a part, according to authorities.⁴ India’s weather department said that winds had brought pollution from stubble burning, or the burning of crop residues, in other states to the capital.