Delhi woke on Wednesday to the season's first 'poor' air quality day, with the Air Quality Index climbing steadily through the day to settle at 245 by 4pm — a sharp jump from Tuesday's 179 and the worst reading the national capital has recorded since July 13.
The day's figure was not only the highest of the current season but also the poorest air quality logged in the city since mid-July, when the index had touched 246. With the winter pollution season now under way, the reading marked a familiar turning point for a city that has battled toxic air every year at this time.
Officials at the Central Pollution Control Board confirmed that the daily average had pushed the city squarely into the 'poor' band of the national air quality scale, which runs from 201 to 300. At such levels, the board cautions, most people can experience breathing discomfort on prolonged exposure, while children, older people and those with heart or lung disease face the greatest risk.
The timing of the deterioration drew immediate attention. It came just a day after Vijayadashami, when effigies of Ravan are traditionally burnt at celebrations across the capital, raising the question of whether the festivities had contributed to the smoky haze. However, no direct link has been established between the Dussehra celebrations and the air quality decline, and officials have stopped short of attributing the spike to the festival.
Responding to the worsening conditions, the Commission for Air Quality Management (CAQM) invoked Stage I of the Graded Response Action Plan (GRAP) across the National Capital Region. The emergency framework, which has governed Delhi-NCR's pollution response since 2017, lays down a set of escalating curbs that kick in as the air quality deteriorates through four stages.
Under Stage I, which applies when the AQI falls in the 'poor' range of 201 to 300, enforcement agencies are required to strengthen dust-control measures at construction sites and along roads, prevent the open burning of garbage and biomass, check pollution-under-control certificates of vehicles, act against visibly polluting and overage vehicles, restrict inter-city buses that do not comply with prescribed norms, intensify inspections of polluting industries, and ensure mechanised road sweeping and water sprinkling across the city.
The action plan escalates further if pollution worsens. Stage II is triggered in the 'very poor' band of 301 to 400, while Stage III applies to 'severe' pollution in the 401 to 450 range. Stage IV, described as 'severe plus', is invoked when the index crosses 450 — the most stringent level, which can bring measures such as restrictions on diesel trucks and bans on non-essential construction. For now, however, the region remains under the first and mildest tier of curbs.
Station-level data on Wednesday painted a mixed picture across the city. The Pusa monitoring station recorded an index of 314 and Jahangirpuri 308, both placing them in the 'very poor' category even as the citywide average remained 'poor'. Sixteen stations, including Anand Vihar, continued to report 'moderate' air quality. Readings were available from 56 of the 59 monitoring stations in the national capital.
The Air Quality Early Warning System has forecast that the air quality is likely to remain 'poor' until at least October 23. Forecasters pointed to meteorological conditions that are unfavourable for the dispersion of pollutants: the ventilation index is expected to stay below 6,000 square metres per second, with average wind speeds under 10 kilometres per hour — conditions that allow particulate matter to linger over the city rather than being carried away.
Data from the Decision Support System for Air Quality Management run by the Indian Institute of Tropical Meteorology in Pune offered a detailed breakdown of what was driving the pollution. Transport within Delhi emerged as the largest single contributor, accounting for 20.5 per cent of the pollution load.
Stubble burning in the surrounding region contributed up to 8 per cent, followed by residential sources at 5.2 per cent, peripheral industries at 4.3 per cent, construction at 2.8 per cent, waste burning at 1.8 per cent and road dust at 1.4 per cent.
The vehicle-emissions figure will sharpen attention on the capital's traffic, which remains the dominant source of year-round pollution even before winter's stubble smoke arrives. With the festive season approaching and winter setting in, enforcement agencies will be under pressure to keep vehicular pollution in check.
Wednesday's reading was also notable in historical context. It was the worst day-after-Dussehra air quality Delhi has recorded since 2021, when the index had stood at 284.
The comparison underlines how the post-festival period has repeatedly coincided with deteriorating air, though meteorologists caution that the correlation is as much about the calendar as about the celebrations — by late October, falling temperatures, calm winds and the beginning of stubble burning across the north-west routinely conspire to trap pollutants over the Indo-Gangetic plain.
Delhi's winter pollution cycle is now a well-studied phenomenon. As temperatures drop, a shallow inversion layer forms close to the ground, preventing pollutants from rising and dispersing. Combined with near-stagnant winds and the seasonal surge in biomass burning, the result is the dense smog that has become synonymous with the capital's November and December.
What varies from year to year is the intensity and timing — and this year, October has delivered the season's first poor day a little earlier in the conversation than some might have expected.
The Delhi government, meanwhile, has already announced a Winter Action Plan that will run from November 1, 2026 to February 28, 2027.
Among its headline measures are denying fuel at 500 petrol pumps to vehicles without a valid Pollution Under Control Certificate, barring non-BS-VI vehicles registered outside Delhi from entering the capital, banning dust-generating demolition and outdoor construction from November 1 to January 31, staggering office timings and mandating 50 per cent work from home, and doubling parking charges to discourage private vehicle use.
In a bid to get more commuters onto public transport, the Delhi Metro Rail Corporation announced it would add 20 trips on weekdays starting Thursday — a move aimed at reducing the number of private vehicles on the road during the high-pollution period.
Environment Minister Manjinder Singh Sirsa noted that Stage I of GRAP had been imposed later this year than in previous years, crediting the Rekha Gupta-led government's sustained efforts and public participation for the delay. The government, he said, has an 11-point air pollution mitigation plan under which nearly 30 agencies are working together.
Health experts have consistently advised caution during 'poor' air days, particularly for vulnerable groups. Doctors recommend limiting prolonged outdoor exertion, keeping windows closed during early morning hours when pollutant concentrations tend to peak, and wearing protective masks when stepping out. Those with asthma, bronchitis or other respiratory conditions are advised to keep prescribed medication at hand and consult a physician if symptoms worsen.
Schools and parents are often among the first to feel the pressure when pollution rises, with outdoor activities and sports frequently curtailed. While no advisories for educational institutions have been issued so far this season, the trajectory of the index over the coming weeks will determine whether such steps become necessary.
The coming days will be watched closely. If the index remains in the 'poor' range, Stage I curbs will stay in force; a further slide toward 'very poor' would trigger Stage II, bringing additional restrictions. For now, Delhi's annual reckoning with its winter air has begun — and with the forecast offering little relief before the weekend, residents are being urged to take precautions and limit their exposure.
(Reporting based on The Hindustan Times and The Hindu.)