The Commission for Air Quality Management (CAQM), responsible for monitoring air quality in the National Capital Region (NCR) of Delhi, implemented stage four restrictions of the Graded Response Action Plan (GRAP) late on Monday. This decision followed a swift escalation in air pollution levels, which had previously led to the announcement of stage three restrictions that same day. The deteriorating air quality was attributed to unfavorable meteorological conditions, prompting immediate action from the commission.
The 24-hour average Air Quality Index (AQI) for Delhi reached 379 by 4 PM on Monday, and by 10 AM on Tuesday, it had climbed to 426. By 2 PM, the AQI further increased to 434. On December 5, the Supreme Court had granted temporary relaxations to GRAP IV restrictions, which had been in effect since November 18, contingent on improvements in air quality.
Initially, the Union Environment Ministry announced GRAP III restrictions around 7 PM on Monday. However, by 11 PM, the situation worsened, compelling the commission to escalate the measures to GRAP IV.
Throughout Monday, the AQI exhibited an upward trend, starting at 351 at 9 AM, rising to 366 by 1 PM and reaching 379 by 4 PM, which led to the invocation of GRAP III. As the AQI escalated to 399 by 9 PM and exceeded 400 shortly thereafter, CAQM shifted to GRAP IV restrictions.
Data from the Central Pollution Control Board indicated that, as of 9 PM on Monday, 23 out of 37 monitoring stations reported AQI levels exceeding 400, with Anand Vihar recording the highest at 460, followed by Rohini at 446, Wazirpur at 444, and Jahangirpuri and Vivek Vihar both at 442. Punjabi Bagh recorded 441.
By 9 AM on Tuesday, further deterioration was observed, with 13 monitoring stations reporting AQI readings over 450. The highest levels reached 471 in both Bawana and Jahangirpuri, while only six stations recorded AQI values between 300 and 400, and the NSIT campus in Dwarka was the only location with an AQI below 300.
The GRAP framework categorizes air quality into four stages: Stage 1 for “poor” (AQI 201-300), Stage 2 for “very poor” (AQI 301-400), Stage 3 for “severe” (AQI 401-450), and Stage 4 for “severe plus” (AQI above 450).
Forecasts from the India Meteorological Department and the Indian Institute of Tropical Meteorology suggest that air quality may continue to fluctuate between the higher end of the ‘very poor’ and ‘severe’ categories in the coming days due to persistent adverse meteorological conditions, according to government reports.
Under the GRAP IV restrictions, both the Delhi government and NCR state governments are expected to suspend physical classes in schools for grades VI–IX and grade XI. Recent Supreme Court rulings have made this mandatory, whereas it was previously optional. However, authorities will need to assess whether to implement this change during ongoing half-yearly examinations.
Additionally, GRAP IV stipulates that state governments in the NCR and the Delhi government must decide on allowing public, municipal, and private offices to operate at 50% capacity, with the remainder working from home. The central government may also issue guidelines permitting work-from-home arrangements for employees in central government offices. Moreover, CAQM has recommended halting truck entry into Delhi, with exceptions for those carrying essential goods or providing essential services. Nevertheless, trucks powered by LNG, CNG, electric, and BS-VI diesel are still allowed to enter the capital.
