Air pollution across Punjab reached alarming levels on Sunday, with Lahore recording an air quality index (AQI) of 292 and once again ranking among the world's most polluted major cities. Nankana Sahib recorded an even higher reading of 685, while Dera Ghazi Khan stood at 611, according to air quality monitoring data reported on 8 November.

Several other Punjab cities also recorded severe pollution in the morning readings. Jhang reached 498, Multan 301, Gujranwala 296 and Faisalabad 294. Readings can vary through the day and between monitoring networks, but the figures place much of the province in the unhealthy to hazardous range.

The deterioration coincides with Diwali, which falls on Sunday, and has raised questions about whether firecracker emissions across the border could add to the pollution burden in eastern Punjab. A Reuters report earlier in the week linked the region's worsening air to vehicle emissions, construction activity and crop-residue burning, and warned that Diwali fireworks could push readings higher still. Across the border, IQAir ranked Delhi the world's most polluted major city on Saturday morning with a reading of 581, while India's Central Pollution Control Board recorded 363.

In response, Punjab Chief Minister Maryam Nawaz Sharif has ordered all deputy commissioners to enforce a complete ban on burning crop residue, telling a review meeting in Lahore that the practice was adding to the province's smog. Smog returns to the plains of northern India and Pakistan each autumn, when falling temperatures and calm air trap smoke and exhaust close to the ground.