GRAP-2 curbs imposed in Delhi as AQI hits ‘very poor’ category at 324

GRAP Stage 2 is a set of emergency pollution-control measures used when Delhi’s AQI reaches between 301 and 400. It matters because authorities use the plan to stop ‘very poor’ air quality from worsening further. The Commission for Air Quality Management, or CAQM, invoked it across Delhi-NCR after the city’s AQI reached 324.

Pollution had risen sharply from 117 on October 31 to 261 on November 1, then to 324 on Monday. The CAQM linked the rise to unfavourable meteorological conditions. Forecasts from the India Meteorological Department and the Indian Institute of Tropical Meteorology indicated that air quality would likely remain very poor.

The Air Quality Early Warning System expected very poor air from November 3 to 5. It forecast a marginal improvement to the poor category over the following six days. Stage 2 therefore reflected both the current pollution level and the risk of continued deterioration.

An AQI of 324 indicates ‘very poor’ air under India’s air-quality categories. It is worse than the ‘poor’ range and below the ‘severe’ threshold, which begins at 401. This level matters because it signals substantially degraded air and prompted emergency measures under GRAP.

Delhi’s citywide AQI rose from 117, classified as moderate, on October 31 to 261, classified as poor, on November 1. It then reached 324 on Monday. The reading was the highest since February 4, when Delhi recorded 339.

Conditions were even worse in some areas. Jahangirpuri recorded an AQI of 436, Rohini recorded 415, and Punjabi Bagh recorded 413, all in the severe category. Of 58 monitoring stations, 37 reported very poor air, 17 reported poor air, and one reported moderate air.

From November 1, Delhi barred petrol and diesel vehicles registered outside the capital if they did not meet BS-VI emission standards. The restriction formed part of winter pollution-control measures and was linked to GRAP-related vehicle curbs. It targeted vehicles considered non-compliant with the prescribed emissions standard.

Electric and CNG vehicles could enter Delhi without this restriction. Petrol and diesel vehicles that met BS-VI standards were also exempt. At the Aya Nagar border, officials turned back vehicles that failed to meet the requirement. Teams also issued fines for violations and incomplete vehicle documents.

Enforcement was jointly handled by Delhi’s Environment and Transport Departments and the traffic police. Checks took place at Rajokri on NH-48, DND Flyway, Ghazipur, Singhu, Tikri and Badarpur. The policy was intended to prevent non-compliant vehicles from entering during worsening winter pollution.

Stricter vehicle checks caused major disruption at Delhi’s interstate borders. Commuters faced long queues as officials checked whether entering vehicles met BS-VI standards and whether their documents were complete. The enforcement was carried out while Delhi’s air quality was worsening and vehicle restrictions were being applied.

Heavy congestion was reported at the Delhi-Gurgaon, Delhi-Noida, Delhi-Ghaziabad, Delhi-Sonipat and Delhi-Najafgarh borders. On NH-48, traffic backed up for several kilometres near the Sirhaul toll plaza. The queues affected both the main carriageway and service roads. Similar snarls developed near Noida and Ghaziabad.

Between midnight on November 1 and noon on November 2, Northern Range teams checked 7,657 vehicles and turned back 609. On November 1, police checked 7,279 vehicles by 8 pm, turned back 714 and impounded 38. Fines were also issued for violations.

The pollution breakdown shows that Delhi’s air came from several sources rather than one alone. Transport was the largest named source in the city’s breakdown, while the broad category of other sources contributed slightly more. These figures helped authorities understand the pollution mix as they imposed GRAP Stage 2.

The Decision Support System for Delhi estimated that transport contributed 19.2% on Monday. Stubble burning contributed 8.4%. Industries in Delhi and nearby areas accounted for 4.2%, while residential activities contributed 4.9%. Other sources made up 20.7%.

The figures also included contributions from neighbouring NCR districts. Jhajjar accounted for 6.9%, Sonipat 5.1%, Gurgaon 2.9%, Rohtak 2.7%, Ghaziabad 2.6%, Baghpat 2.4%, Panipat and Bhiwani 2% each, and Gautam Buddha Nagar 1.9%. This shows the regional nature of Delhi-NCR pollution.

Unfavourable weather can allow pollution to build up when the atmosphere has weak winds or limited vertical mixing. Pollutants released by traffic, industry, burning and homes then remain concentrated near the ground. This matters because people breathe the trapped pollution for longer, while the city’s air-quality readings rise.

The article does not identify the exact weather pattern. It states that the CAQM attributed Delhi’s sharp AQI increase to unfavourable meteorological conditions. Over two days, the AQI rose from 117 on October 31 to 261 on November 1 and then to 324.

Forecasts from the India Meteorological Department and the Indian Institute of Tropical Meteorology suggested that very poor air would continue. The Air Quality Early Warning System expected this category from November 3 to 5, followed by only marginal improvement into the poor category over six days.

PM2.5 is fine particulate matter made up of particles measuring 2.5 micrometres or less. These particles are much smaller than many other airborne particles. Their size matters because the body’s upper airways cannot filter them as effectively as larger particles.

The article identifies PM2.5 as Delhi’s dominant pollutant during the episode. Once inhaled, these particles can penetrate deep into the lungs. They can also enter the bloodstream, allowing pollution exposure to affect more of the body than particles that remain in the nose or throat.

This helps explain why a high PM2.5 level is a serious health concern even when the air does not visibly appear polluted. Delhi’s AQI reached 324, and 37 of its 58 monitoring stations reported very poor air. The city therefore faced both widespread pollution and a dominant pollutant capable of deep penetration.