Air pollution chokes New Delhi every winter, but this year's smog has already derailed everything from transport and road work to schools.

Authorities in India’s capital have shut schools, halted construction and banned non-essential trucks from entering the city after air pollution shot up to its worst level this season.

Delhi recorded air pollution more than 17 times above an acceptable level as worsening smog triggered curbs on trucking and shuttered construction sites and schools.

By Tanvi Mehta NEW DELHI (Reuters) -Toxic smog engulfed much of northern India on Monday and pollution readings in New Delhi hit their highest of this pre-winter season, after dense fog overnight. Visibility dropped to 100 metres in the capital and at least eleven flights were diverted.