Delhi continues to struggle with toxic winter air despite nearly a decade of emergency pollution-control measures. A new analysis by the Centre for Research on Energy and Clean Air (CREA) has found that the city has not achieved any sustained improvement in winter air quality over the past four years.
The average Air Quality Index (AQI) increased from 280 in the winter of 2022-23 to 295 in 2025-26, raising concerns about the effectiveness of the Graded Response Action Plan (GRAP).
The findings have prompted questions about the emergency pollution-control framework, which has been in place since 2016. However, experts caution that the lack of sustained improvement does not necessarily mean GRAP has failed to control pollution peaks.
Nearly four out of every five winter days required restrictions under Stage II of GRAP or more stringent stages, highlighting Delhi’s continued reliance on emergency measures to address its recurring air pollution crisis.
CREA analysed 12 pollution episodes over four winters, examining three instances in each winter when Delhi’s AQI moved from Stage I or II to Stage III or IV. Air pollution worsened during the following week in 10 episodes, while it declined after the other two.
The sharpest increase occurred after the November 2, 2023, episode, when the average AQI rose by 114 points, from 317 before the episode to 431 afterwards. Other significant increases followed the October 29, 2022, episode, when AQI climbed by 100 points, January 3, 2025, when it rose by 94 points, and January 28, 2025, when it increased by 92 points.
According to CREA, pollution levels frequently remained high or worsened in the week after Delhi entered the more stringent stages of GRAP.
However, the analysis does not prove that the restrictions caused pollution to increase or that air quality would have remained unchanged without them.
DID GRAP MAKE ANY DIFFERENCE TO DELHI'S AIR QUALITY?
A separate study titled Possible effectiveness of Graded Response Action Plan restrictions in New Delhi, India, conducted by scientists from the Indian Institute of Tropical Meteorology (IITM), Pune, and the Commission for Air Quality Management (CAQM), found that Delhi could have experienced 60 per cent more hours of severe air quality without GRAP restrictions.
The study also estimated that the number of hours with an AQI above 300 could have been approximately 60 per cent to twice as high in the absence of these measures.
This distinction is important because GRAP is primarily intended to serve as an emergency response mechanism that prevents pollution from worsening during unfavourable weather conditions. It is not designed to eliminate the underlying sources of emissions on its own.
Shambhavi Shukla, programme manager for Clean Air and Sustainable Mobility at the Centre for Science and Environment (CSE), said GRAP primarily helps limit pollution peaks.
She explained that progressively stricter measures are introduced as the AQI crosses thresholds of 300, 400 and 450 to control emissions and prevent further deterioration.
Shukla also pointed out that actual pollution concentrations can exceed the levels represented by the maximum AQI reading of 500. Since the AQI scale is capped at 500, extremely high concentrations of pollutants may not be reflected in a higher index value.
She added that GRAP implementation has evolved over time. Air quality forecasts now allow authorities to impose restrictions in anticipation of worsening conditions instead of waiting for pollution levels to remain dangerously high for an extended period.
DELHI NEEDS YEAR-ROUND POLLUTION CONTROL
According to Shukla, the fundamental problem is that pollution sources continue to operate throughout the year. These include transportation, industrial emissions and various other urban activities.
During winter, weather conditions trap pollutants closer to the ground, intensifying the pollution crisis. Stubble burning and other temporary sources can further increase pollution levels.
Shukla said there was a significant gap between existing policies and their enforcement, stressing the need for more effective implementation of current measures.
She also highlighted the potential of monitoring infrastructure, including Delhi’s integrated command and control centre, to help authorities identify pollution sources and respond more rapidly. However, the information generated by these systems must be translated into immediate action to make a meaningful difference.
CREA has similarly called for reducing emissions at their sources to become the central objective of clean-air policies, with GRAP functioning as a last line of defence during severe pollution episodes.
The findings indicate that Delhi must move beyond its dependence on emergency restrictions during winter. Although GRAP may help limit pollution peaks, lasting improvements will require consistent enforcement throughout the year and sustained reductions in emissions.
