“Delhi’s air got fouler on Monday with the air quality index (AQI) moving above 300 in the ‘very poor’ level.
The Central Pollution Control Board’s (CPCB) National Air Quality Index had Delhi in the “very poor” zone with a score of 326. It was 292 on Sunday and 298 on Saturday, both days in “poor” levels.

Hindustan Times
Read it on Delhiair.org:
Delhi air quality turns ‘very poor’ again, minimum temp falls below 10