The picture is grim indeed. At the time of writing this editorial, Delhi’s Air Quality Index (AQI) stood at 401 (average of past 24 hours at 4 p.m.) as on December 29, 2025, according to the Central Pollution Control Board. This comes under the “severe” category. According to the Swiss company IQAir’s World Air Quality Report 2024, based on particulate matter (PM) 2.5 data, India is ranked fifth amongst the most polluted countries in the world, with an annual average PM 2.5 of 50.6 µg per m3 – over ten times higher than the World Health Organization’s annual guideline of 5 µg per m3.
What contributes to the high PM 2.5 levels in Delhi and NCR? According to a TERI-ARAI study in 2018, the key contributors in winter are secondary ions such as ammonium, nitrate and sulphate (26 per cent); vehicles (20-23 per cent); biomass burning (22 per cent); dust (15 per cent); industry (10-13 per cent) and diesel gensets (less than 5 per cent). As per iFOREST, biomass burning (residential and agricultural) contributes to more than 60 per cent of PM 2.5 in Delhi-NCR. Meanwhile, a recent analysis by the Centre for Research on Energy and Clean Air (CREA) finds that up to 42 per cent of PM 2.5 released in India (and around one-third of Delhi’s annual burden) is due to secondary particulate matter: primarily ammonium sulphate. This is formed by sulphur dioxide (SO2), of which India is the largest emitter globally, with at least 60 per cent of emissions being contributed by coal-fired plants.
This points to the need for solutions in the clean energy and mobility sectors. The Commission for Air Quality Management in National Capital Region and Adjoining Areas (CAQM), notes that in the industrial sector, as of November 10, 2025, it has ensured an almost complete transition to cleaner fuels through stricter emission norms. PNG infrastructure is now available in 224 of the 240 industrial areas in the NCR, and over 96 per cent of industries have shifted to approved fuels. A key measure to tackle vehicular emissions is the transitioning of all Delhi-bound intercity buses to cleaner sources of energy (electric vehicles/compressed natural gas/BS-VI diesel). In the renewables’ space, an additional waste-to-energy capacity of about 7,000 tpd as well as 750 tpd of bio-CNG/CBG capacity are being developed. Further, a decline in paddy farm fire counts has also been observed due to the deployment of crop residue management machinery, enforcement measures, the use of biomass for bioenergy generation and the mandating of co-firing in thermal power plants (TPPs). As of CAQM’s December 1, 2025 data, the cumulative paddy farm fire counts in Punjab, Haryana, Uttar Pradesh (NCR), Rajasthan (NCR) and Delhi have reduced from 78,550 in 2021 to 6,080 in 2025. Even though the air quality in Delhi remains serious, overall, the government’s efforts have somewhat borne fruit. CAQM reports that the average AQI in Delhi during January 1-November 9, 2025, was 175, compared to 189 during the same period last year.
That said, it certainly is not sunshine and rainbows in the NCR. Several concerns exist that merit attention. One, data on the reduction in farm fires (not an ideal proxy for burnt area) remains contested, based on discrepancies in satellite data. Two, the exemption of around 78 per cent of coal-fired TPPs from installing flue gas desulphurisation systems does not bode well, given that it weakens control of SO2 emissions, the core driver of PM 2.5, as per the CREA study. Three, meeting the biomass co-firing mandate in TPPs is still a challenge for plant operators. In fact, CAQM recently issued show cause notices to six TPPs within a 300 km radius of Delhi for non-compliance with biomass co-firing norms.
In this haze, policymakers should not lose sight of the broader objective of the energy transition. Ensuring clean air is as important as reducing dependence on imported fossil fuels. Going forward, focusing only on renewable capacity addition, while breathing hazardous air due to emissions from TPPs, industries, biomass burning and vehicular emissions, is akin to missing the forest for the trees.
