"Delhi world's most polluted major city on eve of Diwali"

Delhi was the world's most polluted major city on Saturday morning, according to Swiss air quality monitoring group IQAir, as the national capital braced for worsening pollution ahead of Diwali celebrations on Sunday, Reuters reported.

According to IQAir's live pollution ranking, Delhi was placed first among the world's major cities at 10.35 am, recording a US Air Quality Index (AQI) of 581. The reading was more than twice that of neighbouring Pakistan's Lahore, which recorded an AQI of 285.

However, India's Central Pollution Control Board (CPCB) recorded Delhi's AQI at 363 at 10 am, placing it in the 'very poor' category. The two readings are not directly comparable as IQAir and the CPCB use different scales and methodologies.

The pollution situation comes amid forecasts of severe air quality conditions ahead of Diwali, which is traditionally marked by widespread firecracker use, further adding to pollution levels.

Authorities have directed schools in Delhi and surrounding areas to offer online classes and encouraged people to work from home to limit exposure to polluted air.

Friday's air quality in Delhi was reportedly the worst recorded on the eve of Diwali in eight years, according to local media reports citing official data.

Air pollution is a recurring problem across several parts of northern India during winter, when cold and heavy air traps vehicle emissions, construction dust and smoke from crop-residue burning, preventing pollutants from dispersing.