Delhi’s Winter Pollution Curbs Return, But Do They Actually Work?
Every winter, Delhi faces a familiar cycle: air quality deteriorates, authorities impose restrictions, and residents wait for pollution levels to fall. Past data suggest that the strictest measures under the Graded Response Action Plan (GRAP) have often coincided with a significant improvement in air quality, although the results have not been consistent.
On October 21, the Commission for Air Quality Management (CAQM) invoked Stage I of GRAP across Delhi and the National Capital Region (NCR). If pollution worsens, authorities can introduce more stringent measures. Yet, despite these recurring interventions, Delhi continues to struggle with severe air pollution every winter.
Do the Restrictions Make a Difference?
Previous pollution episodes indicate that Delhi’s Air Quality Index (AQI) has frequently declined after Stage IV restrictions were introduced.
On January 17, 2026, the AQI stood at 400. Within a week, it had dropped to 192. A similar improvement was recorded in November 2023, when the AQI fell from 454 to 218 over seven days.
However, the trend has not been universal. In December 2024, the AQI increased from 379 to 406 during the week after Stage IV came into effect. This suggests that while emergency restrictions may help curb pollution, their effectiveness depends on several factors, including weather conditions and the many sources contributing to the city’s poor air quality.
Stubble Burning Is Only Part of the Problem
Farm fires often dominate discussions about Delhi’s winter pollution. However, estimates from the Ministry of Earth Sciences’ Decision Support System indicate that stubble burning is only one of several major contributors.
Pollution originating in neighbouring cities and surrounding areas accounted for the largest share of Delhi’s PM2.5 pollution, at 37 per cent. Vehicle emissions were the second-largest contributor, accounting for 20.8 per cent, while stubble burning contributed 10.9 per cent.
The figures highlight the importance of addressing pollution across the wider NCR, alongside measures targeting transport and agricultural fires.
Delhi is also set to prohibit the entry of vehicles that do not meet Bharat Stage VI emission standards from November 1, 2026, to January 31, 2027, as part of efforts to reduce vehicular pollution.
What Do the Previous Episodes Show?
An assessment of seven pollution episodes found that five were followed by a substantial decline in AQI after Stage IV restrictions were imposed. One episode recorded only a modest improvement, while another saw pollution levels rise.
In December 2025, for example, the AQI declined by just 33 points, falling from 431 to 398. The limited improvement underlines the difficulty of controlling pollution through restrictions alone.
Although the overall pattern suggests that the strictest GRAP measures can help, the results vary from one episode to another. A decline in AQI after restrictions are introduced also does not, by itself, establish that the measures were solely responsible for the improvement.
Why Might Stage IV Restrictions Work?
One possible explanation is that Stage IV includes tougher restrictions on certain vehicles, including some petrol and diesel vehicles and trucks. Limiting the movement of high-emission vehicles can reduce the amount of pollution released into the air.
However, Delhi’s air quality is influenced by more than traffic. Emissions from neighbouring urban areas, construction activity, industrial sources, agricultural fires and weather conditions can all affect pollution levels.
The recurring winter crisis suggests that emergency restrictions may provide temporary relief, but they cannot replace sustained efforts to reduce emissions throughout the year. Tackling pollution across Delhi and the wider NCR, improving transport-related emissions and addressing other major sources will remain essential to achieving cleaner air.
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