Exclusive | CPCB awards ARAI-led consortium to prepare Delhi-NCR’s new emission inventory and pollution source studies

The decision was taken on December 2, during the 34th meeting of CPCB’s Project Appraisal and Approval Committee, which deliberates on the utilisation of funds collected through the Environment Protection Charge (EPC). CPCB and the consortium will sign a memorandum of understanding on the project.

EPC has been levied at 1 per cent since 2016 on high-end luxury diesel cars of 2,000 CC, as per the Supreme Court’s orders.

CPCB has directed the consortium to begin preparatory activities to commence work on studies from January 2026.

Concurrent studies

The scope of the study involves developing a high-resolution, dynamic regional emission inventory (500m x 500 m) for Delhi and all districts of the National Capital Region, as well as new NCR-specific emission factors and particulate source profiles.

Two studies — a 20-month-long one on the development of baseline emissions inventory, its validation, and source apportionment, and another 15-month-long one on NCR-specific emission factors and particulate source profiles — will be carried out concurrently, as per official documents.

The move is significant as the question of outdated pollution inventory and apportionment studies has vexed policymakers this season, and the Prime Minister’s Office, too, sought to expedite work on fresh studies. Secondly, the decision support system (DSS), launched in 2021 to inform targeted actions by estimating daily contributions to pollution from various sources, has been relying on dated emissions inventory made as part of the Centre’s SAFAR project and one by TERI-ARAI.

An emission inventory study involves analysing all sources of pollutants affecting the region during a specific period and time. Using that data, one can study the contribution of each pollutant.

The second part of the study will focus on emission factors and profiling particulate matter sources. Emission factor analysis typically refers to the amount of pollution released into the atmosphere from different activities, helping estimate emissions from myriad sources of air pollution.

It quantifies the amount of pollutant released per unit of activity, such as the quantity emitted when a litre of petrol or other fuel is burnt.

Emissions inventory

Meanwhile, particulate matter profiling is the fingerprinting of emissions that helps identify the chemicals emitted by specific sources. This profiling helps determine the contributions of different sources to particulate matter pollution.

As per both SAFAR and TERI-ARAI emission inventories, the transport sector accounted for the highest – 41 per cent and 39 per cent emissions, respectively, for Delhi, while wind-blown emissions, including construction dust, accounted for 21 per cent and 26 per cent, respectively.

The share of industrial pollutants, however, showed significant variation. SAFAR’s inventory showed 19 per cent contribution from industry, and the TERI-ARAI study found it to be 3 per cent.

Earlier this year, CAQM noted inconsistencies in existing approaches to emission inventory and source apportionment, leading to resultant variations.

It constituted a steering committee for identifying polluting sectors and activities in NCR; standardising methodologies for developing inventories and carrying out source apportionment; and developing updated emission factors and source apportionment strategies, including real-time models.

Based on this steering committee’s recommendations, CAQM developed a standard framework in April 2025 for the development of an up-to-date emission inventory and emission-based source apportionment to identify pollution sources in Delhi-NCR.