New Delhi: Between October and February, pollution levels spiked across the country – more than it did the winter before that – shows data analysed from continuous ambient air quality monitoring stations by the Centre for Research on Energy and Clean Air. Of the 238 cities – that include cities covered under the National Clean Air Programme and others – 204 did not meet India’s permissible safe levels for fine particulate matter (or PM2.5, particles that have a diameter of 2.5 microns or less), a major air pollutant. This is far higher than the number in the winter of 2024-25: 173. As per India’s National Ambient Air Quality Standards (NAAQS), annual PM2.5 concentrations have to be less than 40 µg/m³. None of the 238 cities this winter met the World Health Organisationʼs (WHO) PM2.5 guideline of 5 μg/m³ – just like the previous winter.NCAP cities versus othersThe Delhi-based Centre for Research on Energy and Clean Air (CREA) regularly analyses data from Continuous Ambient Air Quality Monitoring Stations (CAAQMS) released by the Central Pollution Control Board (CPCB). For its latest analysis to look at levels of winter pollution, CREA used CPCB data from October 1, 2025, to February 28, 2026. The team used data from cities with at least 80% data availability during this period.Per the CREA report released on March 6, cities covered under the National Clean Air Programme did not really fare better than Indian cities that were not under the project. The Programme, launched in January 2019, aims to improve air quality in 131 cities (non-attainment cities and Million Plus Cities) in 24 States/UTs by achieving reductions up to 40% in PM10 concentrations, or achievement of National Ambient Air Quality Standards for PM 10, by 2025-26.Of the 96 NCAP cities with adequate data, 84 recorded winter 2025-26 average PM2.5 concentrations above Indiaʼs NAAQS, while all 96 cities exceeded the WHO guideline. Non-NCAP cities also showed a similar pattern: of the 142 cities analysed, 120 recorded PM2.5 concentrations above Indiaʼs national standard, and all 142 exceeded the WHO guideline.Regional trendsIn the Indo-Gangetic Plain (IGP), 75 out of 79 cities exceeded the national PM2.5 standard, while only four remained within the prescribed limit. In the National Capital Region (NCR), 28 of the 29 monitored cities recorded sufficient data coverage. None of these 28 cities complied with the national standard, per the report.Across India, the distribution of PM2.5 AQI categories during winter 2025-26 showed that only 19 cities came under the ʻGoodʼ category (0-30 μg/m³), while 129 cities recorded ʻSatisfactoryʼ air quality (31-60 μg/m³). As many as 65 cities fell under the ‘Moderateʼ category (61-90 μg/m³), while, 13 cities reported ʻPoorʼ air quality (91-120 μg/m³) and 12 cities recorded ʻVery Poorʼ air quality (121-250 μg/m³).At the state level, Haryana recorded the highest number of cities where all monitored locations exceeded the PM 2.5 NAAQS, with 24 cities breaching the standard. Andhra Pradesh (nine cities), Punjab (eight cities), West Bengal (seven cities) and Gujarat (six cities) also recorded PM2.5 concentrations above Indian permissible limits. Rajasthan (33 of 34 cities), Maharashtra (30 of 31 cities), Bihar (23 of 24 cities), Uttar Pradesh (17 of 20 cities), Odisha (13 of 14 cities), and Madhya Pradesh (11 of 13 cities) also recorded high proportions of cities exceeding the national standard.Chamarajanagar in Karnataka was the cleanest city in India during the winter of 2025-26, with an average PM 2.5 concentration of 19 μg/m³. The ten cleanest cities included eight cities from Karnataka and one each from Madhya Pradesh and Meghalaya.Most polluted citiesAmong Indiaʼs megacities, Delhi (163 μg/m³), Kolkata (78 μg/m³), Mumbai (48 μg/m³), and Chennai (44 μg/m³) recorded winter 2025-26 average PM2.5 concentrations above the national standard. Bengaluru recorded an average PM2.5 concentration of 39 μg/m³, slightly below the NAAQS limit.Ghaziabad ranked as the most polluted city in India, recording an average PM 2.5 concentration of 172 μg/m³. Noida came second, with an average concentration of 166 μg/m³. Delhi ranked third, recording the average PM2.5 concentration of 163 μg/m³. During winter 2025-26, Delhi experienced 18 ʻSevereʼ days, 87 ʻVery Poorʼ days, 24 ʻPoorʼ days, 15 ʻModerateʼ days, six ʻSatisfactoryʼ days, and only one ʻGoodʼ day.This is entirely contradictory to what Union environment minister Bhupender Yadav said in January this year – that good air days (recording an AQI of 0 to 200) had increased in Delhi to 200 last year, when compared to 116 in 2016. However, as The Wire has reported, there is a difference in what Yadav defined as ‘good’ days, and what the AQI officially delineates as ‘good’. Officially as per India’s NAAQS, ‘Good’ refers to only the lowest AQI category (0-50), which causes only minimal impact to human health. Both the ‘Satisfactory’ and ‘Moderate’ categories (AQI ranges from 50-100 and 100-200) come with health impacts – “May cause minor breathing discomfort to sensitive people”, and “May cause breathing discomfort to people with lung disease such as asthma, and discomfort to people with heart disease, children and older adults”, respectively. So, considering a range of 0 to 200 in AQI – as Yadav and his ministry have done several times including in this press release – means that the Good, Satisfactory and Moderate categories are all clubbed into one and collectively called “good air quality days”, even though two of those categories are not ideally “good” because they do come with health impacts. Greater Noida, Bahadurgarh, Dharuhera, Gurgaon, Bhiwadi, Charkhi Dadri and Baghpat – in that order – were the other cities in the list of the ten most polluted cities. Uttar Pradesh and Haryana accounted for four cities each among the top ten most polluted cities, along with one city each from Delhi and Rajasthan.‘Non-compliance continues’“The comparison between the last two winters shows that widespread non-compliance continues, with more cities breaching the national standard in winter 2025-26 than in the previous winter. While the Commission for Air Quality Management (CAQM) has set PM2.5 reduction targets for the NCR region, similar nationwide PM2.5 reduction targets are needed with a stronger focus on controlling gaseous pollutants such as sulphur dioxide (SO₂), nitrogen dioxide (NO₂) and volatile organic compounds (VOCs), which contribute to the formation of secondary PM2.5 and ozone (O3), a major component of particulate pollution,” said Manoj Kumar, India Analyst, CREA, in a statement on March 6.