Lahore topped Swiss group IQAir's ranking of the world's most polluted major cities for a second consecutive day on Tuesday, as the Punjab government blamed fireworks from Diwali celebrations in neighbouring India for the toxic air blanketing the city.

IQAir put Lahore's air quality index (AQI) at 263, a level the group categorises as "very unhealthy". The city's concentration of PM2.5, fine particles small enough to penetrate deep into the lungs, was 37.2 times the World Health Organization's annual guideline, IQAir said.

Punjab Senior Minister Marriyum Aurangzeb said pollutants had been carried into the region by light winds and air drifting from India in the aftermath of Diwali, when firecrackers set off over the weekend blanketed much of northern India and Pakistan in smog.

Smog across Punjab's cities

Poor air quality was not limited to Lahore. IQAir also recorded an AQI of 283 in Faisalabad, 245 in Peshawar and 228 in Gujranwala, showing that several major cities were breathing unhealthy air. Delhi ranked as the world's second-most polluted major city on Tuesday, with an AQI of 188.

Lahore has grappled with poor air quality in recent weeks as seasonal smog blankets large parts of Pakistan during the winter months. The city's air has repeatedly ranked among the worst in the world this month, and anti-smog guns spraying water have been used in the city in an effort to settle dust and pollutants.

Air quality readings change through the day, and IQAir's city ranking is a snapshot based on the latest station readings. The figures reported on Tuesday reflect conditions at the time of measurement rather than a daily average.

Cricket moved out of Lahore

The smog has already disrupted the cricket calendar. The Pakistan Cricket Board said on Tuesday that the second Test of the series against Sri Lanka, scheduled for 17 to 21 November, had been moved from Lahore to Rawalpindi because of worsening smog. Rawalpindi is currently hosting the series opener.

Air-quality concerns have disrupted cricket schedules in Pakistan before, and the board's decision underlines how far the smog is now reaching beyond daily life into major public events.

What happens next

The Punjab government has pointed to cross-border drift as a driver of the current episode, while the underlying seasonal pattern of winter smog in the region continues. Residents have been advised in past smog episodes to limit outdoor activity when readings are high, although no new city-wide restrictions were reported in Tuesday's coverage.

With the smog season under way, Lahore's position at the top of the global ranking is likely to remain a focus of public debate in the coming days, both over its causes and over what the provincial government does next.