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Delhi’s air pollution fight needs year-round action across Indo-Gangetic Plain: Expert
The expert said tackling air pollution requires sustained, year-round action across the Indo-Gangetic Plain (IGP)
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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:
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.
Deep Dive
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.
Is Grap delivering results?
Yes and No. Grap limits emissions by restricting polluting activities, which is important because emissions are one factor we can control, unlike meteorological conditions. Grap used to be invoked only after pollution levels had peaked. A recent notification now specifies invoking Grap before ground conditions worsen. Grap is still limited to NCR, although a large chunk of pollution still comes from outside NCR. Thus, Grap should be extended across the IGP region to see its full impact. In the long run, we need to shift from episodic Grap measures to proactive air quality management throughout the year.
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. The exact contribution of stubble varies by fire incidents and needs to be monitored on a day-to-day basis. IITM publishes weekly data, which are usually below 20%.
To quantify the exact contribution of each sector, an India-level emission inventory is needed. Mitigation efforts must address all sectors, including transport, hyperlocal sources, MSME industries and clusters, waste burning, waste-to-energy plants, and crematoria. A holistic approach is essential to tackle the problem effectively.
Beyond emergency measures, what needs to change? What are the structural interventions that India needs to prioritise if it wants to bring down pollution levels sustainably?
We are still very much in reactive mode, focusing only on emergency measures every October and November. While India has made significant progress in monitoring and understanding the science and policy, we are far from done. There are several priorities that India needs to pursue on a war footing through sustained, year-round action across the country.
We need to invest in and develop a national emissions inventory that is public and updated periodically. We need to invest more in air quality and understand the transboundary nature of pollution. Air pollution does not respect state boundaries.
We need to invest more in monitoring. Delhi is an anomaly. For the rest of India, monitoring is still a very urban and peri-urban exercise. More monitoring is needed, particularly in rural areas. At the same time, we have to focus on PM2.5 and gases. Some state pollution control boards still focus only on PM10 measurements, even though gases are key precursors for secondary pollutants.
Policy effectiveness must be studied for sectoral actions. At the moment, we analyse performance by assessing expenditure and actions taken. We do not truly know the ground impact of these measures. We have to promote the monitoring of super pollutants like tropospheric ozone and black carbon and integrate them into our climate goals.
