A new independent study brings a mixed bag of news for Chennai's residents. While the city's air pollution levels have shown a significant downward trend over the last ten years, the air quality still falls short of safe breathing standards.
A Decade of Gradual Improvement
Research conducted by Climate Trends, an independent consultancy focused on climate change, indicates a promising 34% improvement in Chennai's Air Quality Index (AQI). The data, gathered from continuous ambient air quality monitoring stations, shows the yearly average AQI dipping from 114 in 2015 to 75 in 2025.
The most notable progress occurred after 2020, with AQI levels consistently ranging between 68 and 75. The best annual average was recorded in 2021 at 66.21. The study tracked data from eight monitoring stations in Chennai from 2015 to November 15, 2025.
Officials Cite Key Measures, Experts Urge Caution
Tamil Nadu Pollution Control Board (TNPCB) officials attribute the post-2020 improvement to several emission reduction initiatives. M Saravanakumar, Member-Secretary of TNPCB, highlighted specific actions: the replacement of traditional furnace oils with high-purity super kerosene in industries, a rise in LPG and CNG vehicles, and consistent mechanical clearing of road dust by local bodies.
Despite these efforts, researchers sound a note of caution. B Palak, research lead at Climate Trends, emphasized that even with improvements, the AQI values are only 'satisfactory,' not 'safe.' The report states that none of India's major cities, including Chennai, has met the safe air quality standard, which is an AQI between 0 and 50.
Data May Not Reflect Ground Reality, Say Experts
Some local climate experts and environmental engineers question whether the averaged data fully captures the on-ground situation. V Prabhakaran, an environmental engineer, pointed out that AQI levels vary across the city—from 'poor' in northern parts to 'moderate' in southern and central regions. Averaging these readings might present an overly optimistic city-wide picture.
Prabhakaran also raised concerns about the calibration and accuracy of the monitoring machines, noting a lack of transparency in maintenance records.
In comparison to other major Indian cities, Chennai fared better. The study noted that Delhi, Vizag, and Ahmedabad logged AQI levels in the three-digit range in 2025, indicating much poorer air quality. The journey for Chennai, however, is far from over. While the trend is positive, achieving truly safe air for its citizens remains a critical challenge ahead.
