Pranav B Prem

The National Green Tribunal (Principal Bench, New Delhi) has taken cognisance of the alarming rise in ground level ozone pollution across several major Indian cities, highlighting a critical yet under-addressed urban air quality concern. The matter stems from a report published by Down To Earth on August 6, 2024, titled “CSE Report Finds Dangerous Increase in Ozone Pollution Across Urban India.”

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Hearing the matter on September 26, 2025, a Bench comprising Justice Prakash Shrivastava (Chairperson) and Dr. A. Senthil Vel (Expert Member) examined data submitted by the Central Pollution Control Board (CPCB) in its latest report dated September 25, 2025. The report provided a detailed analysis of ozone concentrations recorded across 178 monitoring stations in ten major metropolitan regions — Delhi-NCR, Mumbai, Kolkata, Hyderabad, Bengaluru, Chennai, Pune, Ahmedabad, Lucknow, and Jaipur.

Taking note of the CPCB’s findings, the Tribunal observed that widespread ozone exceedances were being reported across diverse climatic zones and emission profiles, reflecting a systemic environmental challenge. The CPCB’s data revealed that 8-hourly exceedances beyond the 2% threshold were observed at 65 out of 178 monitoring locations during 2023. Region-wise, exceedances occurred at 25 locations in Delhi-NCR, 22 in the Mumbai Metropolitan Region, 6 in Pune, 5 in Jaipur, 2 in Hyderabad, 1 each in Bengaluru, Chennai, Ahmedabad, Lucknow, and Kolkata.

The report further indicated 1-hourly exceedances at nine monitoring sites, mainly in Delhi-NCR, Mumbai, and Pune. During the summer of 2023, violations were recorded at ten stations, which increased sharply to 24 stations in summer 2024, including 21 within Delhi-NCR. Notably, night-time exceedances were also recorded at eight locations, pointing to persistent ozone accumulation in the lower atmosphere.

The CPCB attributed these elevated levels to complex photochemical reactions involving nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide (CO), and methane (CH₄) in the presence of sunlight and heat. These precursors primarily originate from vehicular emissions, industrial processes, and thermal power generation, while natural contributors include biogenic VOCs, wildfires, and soil-based nitrogen emissions.

The Tribunal noted that the problem was particularly severe in Delhi-NCR and Mumbai, where dense vehicular traffic, industrial clusters, and meteorological conditions facilitate photochemical smog formation. The CPCB also referred to its earlier report filed in O.A. No. 605/2024, proposing a comprehensive study to identify and recommend targeted strategies for controlling ozone and its precursor pollutants.

During the proceedings, it was informed that the Ministry of Environment, Forest and Climate Change (MoEF&CC) had endorsed the CPCB’s proposal and recommended the formation of an Expert Committee comprising specialists in atmospheric science, air quality management, and environmental engineering. In an earlier order dated August 21, 2025, the Tribunal had directed the Ministry to submit the proposed Terms of Reference and list of experts for the committee within four weeks.

At the present hearing, counsel for the CPCB sought that the instant matter (O.A. No. 1069/2024) be heard jointly with O.A. No. 605/2024, considering the overlapping subject matter and common reliefs sought. Accepting the request, the Bench ordered both cases to be clubbed for joint consideration.

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Listing the matter for further hearing on November 12, 2025, the Tribunal directed the MoEF&CC to apprise it of the progress made in constituting the Expert Committee and the measures proposed to mitigate ozone formation. The Bench observed that the findings underscore a serious environmental and public health issue requiring coordinated national action through scientific assessment, emission source mapping, and policy interventions. Ground level ozone, a secondary pollutant and a major component of urban smog, poses significant threats to human health and agriculture, being linked to respiratory illnesses, reduced lung function, and crop damage. By monitoring the issue and ensuring expert-led evaluation, the Tribunal reaffirmed its commitment to fostering data-driven environmental governance and promoting evidence-based strategies to address complex air quality challenges.

Appearance

Respondents: Ms. Praveena Gautam, Mr. Pawan Shukla, Ms. Tissy A. Thomas & Mr. Rohan Bansla, Advs. for MoEF & CC Mr. Srinivas Vishven, Adv. for CPCB

Cause Title: News Item titled “CSE report finds dangerous increase in ozone pollution across urban India” appearing in Down To Earth dated 06.08.2024.

Case No: Original Application No. 1069/2024 

Coram: Justice Prakash Shrivastava (Chairperson), Dr. A. Senthil Vel (Expert Member)