4 min readNew DelhiJan 21, 2026 12:16 PM IST
First published on: Jan 21, 2026 at 08:34 AM IST
The Commission for Air Quality Management (CAQM) — the pollution watchdog for Delhi-NCR — has said that a source apportionment study has been launched to prepare a new inventory of emissions.
The study will employ high-resolution mapping to track sources — from household heating to crop residue burning — to strengthen the region’s Decision Support System (DSS), a real-time tool to keep a tab on Delhi’s dynamic pollution sources.
The move comes after a CAQM expert panel noted that different studies often yielded different results due to “varying time periods, different locations, different chemical constituents analysed, and different modelling assumptions”. The Supreme Court-mandated panel emphasised that a “unified, data-driven approach” is essential to reduce emission uncertainty and support effective air quality management.
The Indian Express had reported last month that a consortium of institutions led by the Automotive Research Association of India (ARAI), a research body affiliated with the Ministry of Heavy Industries, has been tasked with the study aimed at preparing a new emissions inventory.
The commission said findings of the new study will be integrated into the Air Quality Early Warning System and DSS to get more accurate and real-time data. The consortium — which also includes IIT Delhi, TERI, and IITM Pune — will map emissions on a high-resolution 500 m x 500 m grid.
On Monday, the CAQM released a report titled ‘Identification of the causes for worsening AQI in Delhi-NCR,’ which stated that secondary particulates, formed out of gases emitted by primary sources like vehicles and biomass, contributed significantly to pollution.
“The atmospheric chemistry within IGP (Indo-Gangetic Plain) airshed significantly amplifies particulate pollution through secondary aerosol formation,” it added.
“It has been recognised that Delhi-NCR’s air quality is influenced by both local sources and transboundary effect of regional movement of pollution across the airshed.”
The report underlined that Delhi’s pollution profile shifts drastically between seasons. While dust from roads and construction is the dominant pollutant in summer (27%), winter see a surge in combustion-related emissions. The report identified secondary particulates from gaseous emissions as the largest component of winter pollution (27%). These particles are not emitted directly, but formed through chemical reactions of precursor gases emitted by vehicles and industries.
Transport emerged as the primary source, contributing 23% to the winter pollution load. Experts pointed out that beyond tailpipe exhaust, the sector’s impact is aggravated by non-exhaust emissions such as brake wear, tyre abrasion, and resuspended road dust. The “daily influx of vehicles from outside the city” and traffic congestion leading to inefficient combustion were cited as critical factors.
Meanwhile, biomass burning and municipal solid waste, residential heating, and crop residue burning, account for around 20% of PM2.5 concentrations in winter, it said. The report also noted that while crop residue burning is concentrated in a 30-day window in October-November, it can contribute up to 40% of Delhi’s pollution load during peak harvest season.
However, the experts cautioned that the severe winter spikes are not solely due to increased emissions, but driven by meteorology. The report describes a “lid” effect where low wind speeds and a shallow Planetary Boundary Layer (PBL) trap pollutants close to the ground, preventing dispersion.
The commission said findings of the new study will be integrated into the Air Quality Early Warning System and DSS to get more accurate and real-time data. (file) 
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