India, Dec. 4 -- Delhi's air quality deteriorated again on Thursday, sliding back into the "very poor" category after a brief morning improvement. The city's 24-hour average AQI rose to 304 by evening, according to the Central Pollution Control Board (CPCB).

Earlier in the day, Delhi had shown slight relief with an AQI of 299-just within the "poor" bracket-before pollution levels climbed once more by late afternoon. Data from CPCB's SAMEER app showed that 27 of the 40 monitoring stations recorded "very poor" air quality, with Nehru Nagar posting the highest reading at 362.

Over the past week, the capital has witnessed dramatic fluctuations in pollution levels: an AQI of 279 on November 30, climbing to 304 on December 1, then spiking to ...