Grap-4 is back; schools set to go 'hybrid'

Delhi's air quality index (AQI) tipped into the "severe" zone on Monday evening for the first time in 23 days, snapping a period of relatively reprieve and prompting central panel to reimpose a host of curbs in NCR as part of stages 3 and 4 of the Graded Response Action Plan (Grap).

- Jasjeev Gandhiok

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Delhi recorded a 24-hour average AQI of 379 at 4pm on Monday, with the number rising to 404 at 11pm, as pollution levels spiked dramatically in two days. Delhi clocked an AQI of 294 (poor) at 4pm on Sunday and 193 (moderate) at the same time on Saturday.

This deterioration was largely due to a significant drop in wind speeds that allowed local pollutants to concentrate, said experts.

While Stage 3 was initially announced during the day, a steady increase in AQI prompted the Commission for Air Quality Management (CAQM) to hold an emergency meeting late in the evening, and invoking Stage 4 with immediate effect across NCR.