64% of Delhi’s winter pollution not its doing

Delhi: 19 Sep, 2021 (Times of India)

NEW DELHI: With winter approaching, Delhi could soon find itself in the all too familiar scenario of being enveloped in smog. However, only 36% of this is Delhi’s own doing.
A recent source-apportionment study jointly conducted by The Energy and Resources Institute (TERI) and Automotive Research Association of India (ARAI) indicates that 64% of PM2.5 pollutants blow into Delhi from upwind areas in the neighbouring states, the rest being locally generated.

This again highlights the need for an ‘air-shed’ approach to tackling air pollution in the region.
Vehicle emissions are said to account for as much as 30% of the PM2.5 load of Delhi in winter. The other contributors are biomass burning (23%), industries (20%) and dust and construction (16%).
This source-apportionment study, the most recent for Delhi, was done in 2018. While Delhi government awarded the contract for a real-time study in 2020 to Washington University, it was later deemed unsatisfactory and the new study was awarded to TERI, IIT Delhi and IIT Kanpur. The results are expected this winter.

According to the TERI study, Delhi also contributes 40% to Noida’s winter pollution. Overall, Delhi’s share in the pollution in NCR towns is an average of 16%, signifying cross-boundary transmission of pollutants.

The report says, “The average contribution of Delhi’s own emissions in its PM2.5 concentrations was found to be 36% in winters and 26% in summers. In summers, the contribution of outside sources is higher on account of higher wind speeds and enhanced atmospheric transport of pollutants.

In the NCR towns, the contribution of emissions from Delhi city varies as per their location with respect to Delhi and prevailing wind directions. Noida city, which is downwind of Delhi, receives 28% and 40% of its PM2.5 concentrations from Delhi-based sources in summer and winter seasons, respectively,”

Experts say treating the region as an airshed is crucial if winter pollution is to be tackled efficiently. In its winter action plan, Delhi government has indeed listed inter-state coordination as a key focus area, with environment minister Gopal Rai endorsing an airshed approach.

Dipankar Saha, former head of Central Pollution Control Board’s air laboratory, said air pollution cannot be restricted to a region and the entire Indo-Gangetic plains are affected every winter. “As an airshed region, the entire NCR region can be taken into account, even Punjab and Haryana, where stubble-burning pollutants originate,” said Saha.
“Each state needs to act on its sources simultaneously to bring about overall improvement. If only one state improves its air, wind-borne pollutants from neighbouring states can still nullify the efforts.”

Talking about fixing Delhi’s air pollution problem, Karthik Ganesan, fellow and director (research and coordination), Council on Energy, Environment and Water, said, “The main focus of curbing winter pollution should be to rely on high fidelity forecasting tools that prepare agencies in advance of events of various levels of severity. Timely enforcement of systems such as the Graded Response Action Plan is critical. Restricting activities alone will not suffice.”