Delhi’s air pollution fight needs year-round action across Indo-Gangetic Plain: Expert

Delhi’s air pollution crisis cannot be tackled through emergency restrictions alone and requires sustained, year-round action across the Indo-Gangetic Plain (IGP), says Swagata Dey, policy specialist and group head, Air Quality Policy and Outreach at the Centre for Study of Science, Technology and Policy (CSTEP).

In an interview with HT, Dey spoke ahead of Diwali about the effectiveness of green firecrackers, the limitations of the Graded Response Action Plan (Grap) and why there is a need to expand regional coordination beyond the National Capital Region (NCR)).

Edited excerpts: Swagata Dey of the Centre for Study of Science, Technology and Policy.Every year, there is a debate around firecrackers. This year, green crackers were allowed, as last year. A question remains on how significantly less polluting they are and, more importantly, whether the ban on conventional firecrackers can be implemented if at all.

What is your take on this? Firecrackers are made up of combustibles and toxic heavy metal salts and compounds that give them their characteristic colour. Burning firecrackers is a basic combustion process, producing particulate matter and gases.

With green firecrackers, the only difference is that they are formulated to produce relatively lower emissions. They remain lab-tested in small batches, with no proven quality control at scale, and they still produce smoke.

In India, implementing pollution-related bans can be challenging owing to the scale of the population and enforcement constraints. Although firecrackers have been banned in NCR for almost five years, ensuring compliance has been difficult.

Increasing public awareness, monitoring supply chains, and enforcing strict penalties may help restrict firecracker use in Delhi-NCR. A gradual shift towards alternative ways of celebrating could help reduce dependence on firecrackers.

The government could also support reskilling and livelihood programmes to help firecracker industry workers shift to other sectors. Delhi continues to record alarmingly high pollution levels despite years of interventions, multiple action plans and restrictions.

What does the current situation tell us about the effectiveness of our fight against air pollution? Are we fundamentally getting something wrong, and is there any evidence that the measures taken over the years are slowly working?

It is a combination of both. Our understanding of pollution sources, sectoral contributions, and impacts has evolved. Earlier, we focused only on Delhi-NCR, but it soon became clear that a wider regional approach was needed, leading to the formation of the Commission for Air Quality Management (CAQM).

We are now beginning to consider regional contributions and address air pollution as a transboundary problem. So, we are not fundamentally wrong. We are in the right direction, albeit progressing very slowly. Another area of concern that remains unaddressed is secondary pollutants.

Most of our efforts focus on controlling primary PM, so we largely ignore gases. These are precursors that help form secondary PM and add to the overall numbers. I would not say that nothing is working. I would say that we do not have enough evidence on the impact or lack thereof.

Delhi’s last emission inventory (EI) predates COVID. Since then, several changes have taken place, including clean cooking schemes, deeper penetration of EVs, the phase-out of BS-III vehicles, increased adoption of electric buses, and the introduction of new DG sets.

But we do not have the data to determine the impact of sectoral contributions. An updated EI will help establish whether the measures are working. Every year, we also tend to focus on high pollution levels in September and lose sight of the issue in March.

This year’s pollution figures should be interpreted with caution, as meteorological factors, including the effect of a possible Super El Niño, may also be playing a role. Air pollution does not respect administrative or state boundaries.

We talk about an airshed approach, but do we need to move beyond NCR too? How can we implement this airshed approach properly, without getting into the politics of different state governments? CAQM looks at the NCR, which can be considered an airshed.

But the IGP region is the real airshed. CSTEP’s work on interstate pollution, the ‘Beyond State Boundaries: Quantifying interstate air pollution transport and sectoral solutions in the Indo-Gangetic Plain’ report, shows that all states are both sources and receptors of pollution.

While establishing CAQM for NCR was a step in the right direction, similar oversight and coordination are required across the IGP. The environment ministry and the National Green Tribunal (NGT) have issued directives for states to develop action plans that account for transboundary contributions.

With a common political leadership across NCR states, there is an opportunity to strengthen coordinated action. Air pollution is a shared burden that requires a collective response. CAQM’s jurisdiction could be expanded across IGP, building on the existing model.

Finance is an important concern. One option is to establish funds pooled from existing environmental cess, unused NCAP funds, and philanthropic and CSR contributions. Every winter, stubble burning in Punjab and Haryana becomes a major talking point, often turning into a blame game.

What is the actual contribution of stubble burning to Delhi’s PM2.5 levels during peak episodes, and how should we contextualise it against other sources such as transport, industry and secondary aerosols? It is well established that stubble burning contributes marginally to Delhi’s pollution crisis annually, but more significantly seasonally.

Our modelling simulations indicate that the contribution may reach up to about 15% during the peak winter months. In fact, evidence suggests that a large chunk of wheat stubble is burnt in May, but because of better ventilation, the impact is not seen in Delhi.

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