Kol winter PM2.5 count better than Del’s, best since 2020-’21
Times of India | 19 March 2025
Kolkata: Kolkata's air quality improved this winter with the average PM2.5 concentration dropping to 65 micrograms per cubic metre between Oct 2024 and Jan 2025 against 77 micrograms per cubic metre and 85 micrograms per cubic metre in the past two winters, but it still remained the second-most polluted mega city in the country after New Delhi.
A new analysis by Centre for Science and Environment (CSE) found a rise in winter air pollution in all Indian mega cities — Delhi, Mumbai, Kolkata, Bengaluru, Hyderabad and Chennai — with the intensity of pollution varying due to differing meteorological conditions.
Delhi, positioned in the landlocked Indo-Gangetic Plains, recorded the highest winter pollution levels, followed by Kolkata, at the tail end of the plains.
The other cities benefited from more favourable climatic conditions but still experienced a rise in PM2.5 concentrations because of higher emissions, stagnant atmospheric conditions and reduced pollutant dispersion during winter.
Kolkata's average PM 2.5 concentration of 65 micrograms per cubic metre was the lowest in four years, but localised pollution peaks were a cause for concern.
This winter's peak — 135 micrograms per cubic metre on Nov 2 — was the same as that of the previous winter, but lower than the peaks of the previous two seasons. Among the seven monitoring stations, Ballygunge recorded the highest daily peak at 195 micrograms per cubic metre on Nov 2, indicating persistent localised pollution hotspots.
Ballygunge also had the highest number of bad air days, recording 54 instances of ‘poor' and ‘very poor' AQI. Among the other station, Fort William had 29 ‘poor' and ‘very poor' days, Bidhannagar 24, Victoria 17, Rabindra Bharati University 15 and Jadavpur 13.
Monitoring station data showed that PM2.5 concentrations during winter exceeded the annual average across all key locations in the city. Ballygunge recorded the highest winter average at 80 micrograms per cubic metre, a sharp increase from its annual average of 51 micrograms per cubic metre. Fort William and Bidhannagar also showed similar spikes, with winter averages of 71 micrograms per cubic metre and 67 micrograms per cubic metre respectively, compared to their annual levels of 49 micrograms per cubic metre and 46 micrograms per cubic metre. Even Rabindra Sarobar, which had the lowest annual average at 39 micrograms per cubic metre, saw its winter levels rise to 54 micrograms per cubic metre.
CSE executive director (research & advocacy) Anumita Roychowdhury said the peaking of pollution during winter in any climatic zone signals the underlying issue of persistent air pollution in rapidly urbanising and motorising cities. "The growing impact of local pollution sources intensifies pollution hotspots across urban centres, increasing exposure risks," she said, adding that stricter measures were necessary to address pollution from all sources, especially in cities like Delhi and Kolkata, which face adverse meteorological conditions that increase pollution.
"While Delhi's winter air quality often dominates public discourse, rising pollution levels in other megacities remain largely overlooked," said CSE Urban Lab programme officer Sharanjeet Kaur. "Despite some improvement in seasonal trends, winter pollution continues to be high, or is rising locally."
Air quality trends indicate that pollution levels in Kolkata begin to rise sharply mid-Nov and persist until the end of Jan.