A driver wears a face mask as traffic moves through heavy smog near New Delhi. (EPA Images pic)DELHI: Delhi was the world's most polluted major city on Saturday morning, according to Swiss group IQAir's live ranking, as the Indian capital faced severe pollution forecasts a day before Diwali, the Hindu festival of lights.

India has ordered schools in and around Delhi to offer online classes, and encouraged people to work from home ahead of Diwali on Sunday, which is usually marked by the widespread use of firecrackers that further worsen the air quality.

IQAir ranked Delhi first among the world's major cities at 10.35 am, with a US air quality index reading of 581, double that of Lahore in neighbouring Pakistan, at 285.