Will Delhi’s Winter Air Quality be Any Different this Year, Given Better Indicators Earlier but Recent Deterioration?

Delhi residents experienced an unusual reprieve in 2025 — the capital recorded its best air quality numbers in eight years through September, according to monitoring data. Favourable climatic conditions, including above-average rainfall and consistent wind patterns, kept pollution levels relatively manageable for most of the year. However, as October arrived, so did the familiar haze.

The capital's air quality slipped into the 'poor' category for consecutive days the week before Diwali. With Diwali and flouted norms, traditional crackers being sold openly rather than the green crackers that the Supreme Court mandated to lift the ban for and vehicular and industrial pollution, Delhi had the worst air quality in 5 years. 

Despite a drop by 77.5% in stubble burning this year, a past headache for pollution, Delhi's AQI post Diwali plummeted to concerning levels with average PM 2.5 reaching 488 micrograms per cubic metre – nearly 212 per cent more than the previous year's levels. The highest reading for Diwali night was 676, which is more than 200 times the exposure level prescribed by WHO.

The Air Quality Early Warning System for Delhi forecasts similar conditions ahead. "The transition from September to October is always critical," explains senior scientist Dr. Ravi Chopra, Director of People's Science Institute, Dehradun, "What we've seen this year is that good climatic factors can only do so much when structural pollution sources remain unaddressed. The moment meteorological conditions shift, we're back to square one."

Forecasting Systems and Their Limitations

Delhi's Air Quality Early Warning System provides three-day air quality forecasts and has demonstrated the ability to predict 'very poor and above' pollution episodes more than 80 per cent of the time in recent winters, according to a new Council on Energy, Environment and Water (CEEW) study released in October 2025. The system's performance in predicting severe episodes improved notably in 2024-25, correctly forecasting 5 out of 14 instances compared to just 1 out of 15 the previous year.

Mohammad Rafiuddin, Programme Lead for CEEW's Clean Air vertical, emphasises the system's potential. "Reliable air quality forecasts can play a crucial role in informing citizens of the precautionary measures they should adopt to protect themselves from exposure to polluted air. While Delhi has a fairly reliable system providing air quality forecasts, there is a need to strengthen it further to equip decision-makers to use it to take preemptive mitigation actions. Air quality forecasts should be an integral part of air quality decision-making at the citizen level and at regulatory levels."

However, the CEEW study identifies critical gaps: the system lacks outcome monitoring, doesn't provide actionable short-term pathways for pollution reduction, and operates on outdated emission inventories from 2016-2018. 

The Perfect Storm Brewing

This winter presents a particularly challenging convergence of factors. La Niña conditions are predicted to create stagnant atmospheric conditions conducive to pollution accumulation. The Supreme Court's recent decision allowing a five-day window for firecracker sales and use during Diwali added another layer of concern. It has already proven to be a fatal decision with air levels still at 'poor' or 'very poor', days after Diwali.

Many citizens raised their concerns with us about the many narratives that have been raised with the deteriorating air levels. "My eyes burned when I got out for my morning walk the next morning of Diwali. Everywhere was covered with smog and a blanket of white smoke filled everything," said Narnail Singh, who has been a resident of GK-2 for past 20 years told us while chatting with his friends about the same, "For past many months of this year, one noticed clear blue skies and I expected the Delhi skies of winter would potentially return this year, but cursed we are again with this silver sky thanks to smog and our own actions."

As we contacted a farmer from Punjab to know the scenario of stubble burning, and the ground reality this time, Gurvinder Singh, from Gurdaspur, said, "The poor are always blamed. Many of my relatives have been questioned severely this year for stubble burning, when we are not even doing it. I have also heard from people that many farmers have been locked up and some are charge-sheeted despite the stubble burning not being done this year."

Dr. Chopra states the same, "It is not stubble this year, data would show higher black carbon if it were stubble. This year's lingering pollution right now is mainly due to the spike we had during Diwali. If you notice, we are having one of the fastest recoveries in terms of air, but only if we had avoided the Diwali mishap, we could have escaped this period of deterioration as well."

Additionally, attempts to implement vehicular emission controls earlier this year were abandoned following mass public protests.

"We're looking at a policy vacuum meeting adverse meteorological conditions," states Sania Rehmani, climate activist and director of 'There is No Earth B collective'. "The improved air quality through September gave us false hope. But without concrete action on stubble burning, industrial emissions, and vehicular pollution, winter will expose our systemic failures once again."

The CEEW study reveals that whilst the Commission for Air Quality Management theoretically implements the Graded Response Action Plan (GRAP) based on forecasts, in practice, authorities have imposed restrictions only after AQI thresholds were breached rather than pre-emptively. This reactive approach undermines the forecasting system's utility. Just like clockwork, the government has implemented GRAP-II with falling AQI, but it was again a reactionary measure, all while requesting and getting granted a five-day leeway period for firecracker sales for Diwali, adding to public woes.

What Lies Ahead

The contrasting narratives of 2025; eight months of improved air quality followed by October's deterioration highlight a fundamental truth: favourable climate cannot compensate for inadequate pollution control infrastructure. The capital's September success demonstrates what's possible when meteorological factors align favourably. Wind patterns dispersed pollutants effectively, and monsoon rainfall cleansed the atmosphere. But these are temporary reprieves, not solutions.

With La Niña expected to trap pollutants closer to ground level, the stubble burning season approaching in neighbouring states, and limited vehicular controls in place, the signs are concerning. The Supreme Court's firecracker concession resulted in catastrophic levels of pollution, and the absence of a functioning vehicle rationing system further complicated matters.

Whether Delhi's winter air quality will differ significantly from previous years remains uncertain. The late October numbers suggest a return to familiar patterns. The coming months will reveal whether this year's climatic advantages can offset policy inaction, but current indicators offer little room for optimism. For now, as air purifier sales spike and MCD sprinkler trucks try and circle monitoring stations to botch data and falsify it, citizens are bearing the consequences.