India, Nov. 8 -- Delhi wakes up to Diwali on Sunday after its most polluted festival eve in a decade, with a perfect storm gathering over the night to come.

Farm fires in Punjab and Haryana climbed to their highest this season on Saturday - and the Isro satellite's count rose for a 10th straight day, the ground wind fell calm after sunset, and within two hours of the first evening window for firecrackers opening at 8pm, the city's air was 30% dirtier than a night earlier.

All of that came before the festival night itself, when most of the city's firecrackers are burst, and light winds are forecast for Sunday.

The 4pm air quality index (AQI) on Saturday was 369, "very poor" on the Central Pollution Control Board's (CPCB) 0-500 scale and...