GRAP failed to clean Delhi's winter air. Would pollution be worse without it?

The CREA analysis found no sustained improvement in Delhi’s winter air over the past four years, despite GRAP being used since 2016. Average winter AQI rose from 280 in 2022-23 to 295 in 2025-26. This matters because GRAP has become a central tool for managing Delhi’s recurring pollution crisis.

CREA examined 12 pollution episodes across four winters. In 10 cases, pollution worsened during the following week after Delhi moved into Stage III or IV. After the November 2, 2023 episode, average AQI increased by 114 points, from 317 to 431. These results show that pollution often remained high after stricter measures began.

However, the analysis does not prove GRAP caused pollution to rise. It also cannot show that air quality would have been unchanged without the restrictions. The findings instead suggest that emergency controls may limit peaks but cannot replace year-round reductions in emissions from transport, industry, and other sources.

The Graded Response Action Plan, or GRAP, is an emergency framework designed to stop Delhi’s pollution from escalating during severe episodes. It does not permanently remove pollution sources. Instead, it introduces increasingly strong restrictions as air quality crosses specified thresholds.

The system tightens action when AQI crosses 300, 400, and 450. These stages bring progressively stricter measures to reduce emissions and arrest further deterioration. Authorities can also use forecasts to begin restrictions before pollution remains high for a prolonged period. This makes GRAP a preventive emergency response, not just a reaction to recorded pollution.

Its main purpose is to reduce pollution peaks during unfavourable weather. It therefore works alongside, rather than replaces, longer-term measures. The article notes that lasting improvement requires stronger enforcement and sustained cuts in emissions throughout the year, while GRAP remains the last line of defence during severe episodes.

GRAP restrictions were widespread in Delhi. Nearly four in five winter days saw Stage II restrictions or higher. This shows that emergency controls are not occasional interventions; they have become a frequent part of Delhi’s winter response to polluted air.

CREA studied 12 episodes across four winters, examining three episodes in each winter. Across the period from winter 2022-23 to winter 2025-26, average AQI climbed from 280 to 295. That is a 15-point increase, indicating no sustained improvement in overall winter air quality.

The episode results were also troubling. Pollution worsened in the week after 10 of the 12 episodes, while it eased after only two. One major example followed November 2, 2023, when AQI rose 114 points, from 317 to 431. These figures raise concerns about lasting effectiveness, although they do not prove restrictions caused the increases.

A study by scientists from IITM, Pune, and CAQM found that GRAP likely prevented pollution from becoming even more severe. Its estimates show why unchanged or worsening AQI after restrictions does not automatically mean the plan had no benefit.

Without GRAP restrictions, Delhi could have experienced 60 per cent more hours of severe air quality. The study also estimated that hours with AQI above 300 could have been around 60 per cent to twice as high without the measures. GRAP therefore appears to reduce the duration or intensity of pollution peaks.

This does not contradict CREA’s findings. CREA assessed whether air quality improved after severe episodes, while the IITM-CAQM study estimated what might have happened without restrictions. GRAP is intended to prevent escalation during dangerous conditions, not eliminate emissions permanently. Long-term improvement still depends on year-round action at pollution sources.

GRAP is designed to slow or prevent pollution peaks, not to eliminate every source of emissions. Transport, industry, urban activity, and episodic sources can continue releasing pollutants after restrictions begin. As a result, air quality may remain poor or worsen even while emergency measures are active.

Winter weather makes the problem harder. The article explains that winter conditions trap pollutants closer to the ground, increasing concentrations across the city. Stubble burning and other episodic sources can add to this burden. Pollution therefore reflects both ongoing emissions and weather conditions that limit dispersion.

CREA found that pollution worsened during the week after 10 of 12 studied episodes, but it did not establish that GRAP caused those increases. Restrictions may still have prevented even higher peaks. Forecast-based action can help authorities intervene earlier, but lasting improvement requires stronger enforcement and emission cuts throughout the year.

The article identifies persistent pollution sources that operate beyond winter emergencies. Transport, industrial emissions, and other urban activities continue contributing to Delhi’s air throughout the year. Reducing these sources matters because GRAP is only a temporary response when pollution becomes especially dangerous.

Winter restrictions can curb some emissions during severe episodes, but they cannot substitute for consistent enforcement. Stubble burning and other episodic sources can also increase pollution, while winter weather traps pollutants near the ground. Monitoring systems, including Delhi’s integrated command and control centre, could help identify sources and support faster action.

The main need is to shift clean-air policy toward reducing emissions at source. Shambhavi Shukla said the gap between policies and enforcement strategies remains a major problem. GRAP should serve as the last line of defence, while year-round implementation tackles the causes of Delhi’s recurring pollution crisis.

Delhi’s pollution level depends on how much pollution enters the air and how easily it disperses. Transport, industry, urban activity, stubble burning, and other sources add pollutants. Winter weather traps them closer to the ground, worsening the air people breathe. This combination can produce severe pollution episodes.

The AQI converts pollution concentrations into a headline measure. As the AQI crosses 300, 400, and 450, GRAP introduces progressively stricter controls. However, the scale is capped at 500. Shambhavi Shukla noted that pollutant concentrations can exceed the level represented by the maximum AQI reading.

This means a headline AQI of 500 does not necessarily mark the full upper limit of pollution. High emissions and stagnant winter conditions can push concentrations higher without producing a larger AQI number. The system helps communicate danger, but monitoring and direct source reductions remain essential for meaningful improvement.