Delhi spent 78–83% of winter days under GRAP Stage II or higher over the past four winters highlighting the need for year round emission controls and stronger public transport.
Delhi is once again preparing for deteriorating air quality as October draws to a close, raising concerns about the effectiveness of seasonal pollution restrictions. Although late monsoon rainfall and sustained winds provided temporary relief this year experts warn that the underlying causes of the capital’s pollution crisis remain unresolved.
The delayed onset of winter smog has been attributed partly to favourable weather conditions that helped disperse fine particulate matter. However, falling temperatures, weaker winds and the seasonal rise in agricultural residue burning across Punjab and Haryana could worsen pollution levels in the coming weeks.
According to Manoj Kumar, an analyst at the Centre for Research on Energy and Clean Air (CREA), Delhi average winter Air Quality Index (AQI) has fluctuated without showing consistent improvement. The mean AQI rose from 280 in winter 2022–23 to 304 in 2023–24, declined to 285 in 2024–25 and increased again to 295 in 2025–26.
As temperatures drop, the atmospheric boundary layer becomes shallower, trapping pollutants from vehicles, industries and biomass burning closer to the ground. Weather patterns associated with El Niño can also influence regional atmospheric conditions potentially contributing to prolonged periods of stagnant air.
The Commission for Air Quality Management (CAQM) implements the Graded Response Action Plan (GRAP) when pollution levels deteriorate. These measures include dust control requirements and temporary restrictions on certain vehicles and construction activities.
However, CREA’s analysis suggests that emergency restrictions alone have struggled to reverse pollution spikes. Delhi spent approximately 78–83% of observed days under GRAP Stage II or higher across the previous four winters. The analysis also found that in 10 of 12 examined episodes average AQI levels were higher in the week after pollution restrictions tightened than in the preceding week.
Experts stress that these findings do not mean GRAP is ineffective in every situation, but they highlight the limitations of relying primarily on emergency measures after pollution has already worsened.
Environmental activist Bhavreen Kandhari has also raised concerns about gaps in the enforcement of vehicle restrictions, particularly at entry points to the capital. She argues that regulations must be accompanied by effective monitoring, strict implementation and clear assessments of their impact on emissions.
Strengthening public transport is another priority. Experts say improved bus services, better connectivity and more convenient alternatives to private vehicles could help reduce traffic congestion and vehicular pollution.
Beyond transport, Delhi must address other major pollution sources, including road dust, construction activities, garbage burning, inadequate waste management and industrial emissions. Tackling these sources requires coordinated action across the National Capital Region rather than isolated restrictions within the city.
Experts maintain that GRAP remains important during severe pollution episodes, but lasting improvement will depend on reducing emissions throughout the year. Without sustained action on the sources of pollution, Delhi risks repeating the same cycle of winter smog, emergency restrictions and temporary relief.