New CSE assessment shows PM2.5, NO₂ and CO rose in lockstep across Delhi-NCR this early winter.
Air quality remained in the ‘Very Poor’ to ‘Severe’ range despite a marked drop in farm fires.
Smaller NCR towns such as Bahadurgarh, Ghaziabad and Hapur saw more intense smog than Delhi.
Pollution hotspots are expanding across the capital, with new areas appearing year after year.
Experts warn that Delhi-NCR’s air crisis now stems from everyday emissions, not seasonal events.
This winter’s reality has come into sharp focus with Delhi-based think tank Centre for Science and Environment’s (CSE) latest assessment, Toxic cocktail of pollution during early winter in Delhi-NCR, which was released December 1, 2025. Delhi’s air quality has shown no real improvement this winter despite a sharp drop in crop stubble-burning incidents across Punjab and Haryana, it shows. Pollution levels across Delhi-National Capital Region have plateaued at “dangerously high” levels, with local, year-round sources now driving most of the region’s toxic smog.
The early winter period of October and November recorded a tightly linked rise in PM2.5, nitrogen dioxide (NO₂) and carbon monoxide (CO) across Delhi-NCR, all moving almost in tandem through the day, the analysis found. These pollutants spiked during morning and evening traffic hours and remained trapped under shallow winter air, creating a harmful mix that most people inhaled throughout the season.
What makes this winter particularly telling is that farm fire incidents were significantly fewer than usual. Even then, air quality across November stayed locked in the Very Poor to Severe range, showing clearly that local emissions — vehicles, industries, waste burning and construction — now play the dominant role in shaping winter pollution.
Beyond these early winter observations, the longer-term pattern is equally unsettling. Over the past few years, Delhi’s hard-earned improvements in PM2.5 levels have plateaued at a high and unsafe level. Between 2018 and 2020, the city saw meaningful reductions, but the progress has stalled. Annual averages in recent years show little improvement and even a rise last year, signalling that earlier measures are no longer enough to push the city forward.
Looking at early-winter averages (October-November), this year’s levels are slightly lower than last year but almost identical to the three-year baseline, showing that real improvement on the ground has not taken place. This stagnation is a warning that deeper structural changes are now essential to prevent a renewed worsening of air quality.
Beyond the capital, the rest of the NCR had an equally troubling winter. Several NCR towns, often assumed to be slightly better off, have experienced more intense smog than the capital itself. Bahadurgarh recorded one of the longest and highest-intensity smog spells of the season, with levels exceeding those in the capital. Ghaziabad, Hapur, Greater Noida and Noida also saw persistent high-pollution days. Their smog intensities repeatedly crossed hazardous thresholds, proving once again that the entire region now functions as a single, overloaded air basin. Pollution does not stay confined to the capital; it spreads, settles and lingers across cities large and small.
Within Delhi, too, the pollution landscape has spread and become more complex. The number of pollution hotspots has grown quietly over the years, reflecting the changing urban fabric. Older hotspots like Jahangirpuri, Wazirpur, Anand Vihar and Bawana continue to show extremely high particulate levels, but several new hotspots have emerged. Vivek Vihar, Dwarka Sector 8, Sirifort, Patparganj, Nehru Nagar and Alipur have now joined the list, some for multiple years in a row.
These emerging hotspots reflect growing local pressures: increasing traffic volumes, clustered industries, unmanaged waste, construction activity and dense neighbourhoods that trap pollution more easily during winter.
This year also saw a widespread rise in carbon monoxide across the city, with several monitoring stations exceeding the eight-hour standard on more than half the days of the season (Oct–Nov). The synchronised rise of PM2.5 with gases such as NO₂ and CO shows how tightly winter pollution is linked to traffic and combustion sources. It also makes the air far more toxic than PM2.5 levels alone might indicate.
The season, taken as a whole, makes one fact unmistakable: Delhi-NCR is no longer facing winter pollution because of one factor or one event. The problem is now embedded in everyday systems — how we move, build, burn fuel and manage waste. Small or seasonal actions cannot shift this trend. What the region needs is a stronger, long-term transition: cleaner fuels for factories, more electric and zero-emission vehicles, reliable public transport, stricter dust control, better waste management and strong action throughout the year, not just in winter.