The problem of finding source of pollution in Delhi persists | Latest News Delhi

On November 18, as Delhi’s Air Quality Index (AQI) soared to a staggering 494 – the city’s second-most polluted day on record – questions loomed over the reasons behind the sudden spike. Yet, pinpointing the exact sources of pollution proved elusive, as key studies and real-time data systems remain outdated or defunct, leaving a critical void in the battle against Delhi’s toxic air.

Over the past four years, at least three key studies aimed at real-time pollution source identification have either been halted or rendered obsolete.

The Delhi government’s real-time source apportionment analysis, which sought to provide a granular understanding of pollution sources, has been inactive since November last year. The Delhi Pollution Control Committee (DPCC) has struggled to find a suitable institute to operate the equipment needed for the study.

This means that Delhi is left with only one model – the Decision Support System (DSS) under the Union ministry of earth sciences, which can only “estimate” the contribution of pollution sources and relies on a three-year old emissions inventory.

Experts argue that understanding the precise contributors to Delhi’s pollution is essential for formulating targeted interventions and fostering accountability in tackling this persistent crisis.

On November 18, DSS – managed by the Indian Institute of Tropical Meteorology (IITM) in Pune – attributed 46.21% of Delhi’s PM2.5 pollution to “other sources,” which includes cross-border pollutants and contributions from outside the National Capital Region (NCR). It estimated 16.97% of the pollution came from Delhi’s transport sector and 5.32% from Sonepat. Stubble burning, a perennial contributor during winter, was recorded at 19.82% for that day.

But the problem is that all these figures were only released two days later.

DSS’s limitations are further compounded by its reliance on old data and the absence of an archive, which prevents historical analysis.

The platform itself acknowledges that updated emissions inventories are essential for more accurate estimations, but this remains unaddressed. “For more accurate estimation of source-contribution, the latest emission fields are required,” the website states.

Other limitations include data only being available on the website for a period of four days, without having any access to an archive. This means one cannot study the source break-up on previous days.

Previous attempts

Attempts to establish reliable real-time pollution monitoring have faltered repeatedly.

Previous such studies, including those by IIT-Kanpur, have also come under scrutiny for either outdated findings or methodological disagreements with the Delhi government.

Aspersions were cast by Delhi government on the data shared by IIT-Kanpur during its tenure running the source apportionment study. On most days, the study found secondary inorganic aerosols – formed in the air due to incomplete combustion, were the primary source of pollution.

Due to this friction, Delhi government last year decided not to renew the term of IIT-Kanpur.

In August this year, Delhi environment minister Gopal Rai asked DPCC to take over the equipment and restart the study – but nothing has come of it so far.

“We were dissatisfied with how IIT-Kanpur was calculating the sources and their contribution. Thus, the expert institute we choose will first have to revise the methodology. So far, it appears unlikely this will happen this year,” said a DPCC official, adding they were yet to finalise the “expert” institution they were seeking.

An initiative with Washington University in 2020 was similarly scrapped after a year for unsatisfactory results. The study’s data was never made public, with the government scrapping the deal in a year due to “unsatisfactory” results.

Experts emphasise the urgent need to revive real-time source apportionment studies.

IIT-Delhi’s Mukesh Khare, an air pollution expert, suggests even a single centrally located supersite in Delhi could provide valuable insights. “Even having one supersite in Delhi enough, as real-time instrumentation is costly, but if placed in a central location, it should be able to cover different geographical aspects of the city and its pollutants well,” he said.

However, the last comprehensive source apportionment was conducted in 2018 by The Energy Resources Institute (TERI), with the previous one dating back to 2015-16 by IIT-Kanpur—both now considered outdated.

“Source apportionment data needs to be new and accurate in order to take informed decisions. Until we have a realistic and dynamic inventory of all our sources, we cannot plan interventions accordingly,” said Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment (CSE).

Sunil Dahiya, lead analyst at the think-tank Envirocatalysts said absence of accurate data and transparency means blame-game between states will continue. “There need to be multiple sources, sharing accurate information. Data shared by DSS is too old and does not give an accurate picture,” he said.