This year, new system to pinpoint sources of air pollution in Delhi-NCR

An air quality early warning system, developed by the Indian Institute of Tropical Meteorology (IITM), Pune, has been operational in Delhi-NCR since 2018.

A newly developed Decision Support System (DSS) that will attempt to determine the source of air pollutants in Delhi-NCR will be a part of the existing air quality forecasting system this year.

An air quality early warning system, developed by the Indian Institute of Tropical Meteorology (IITM), Pune, has been operational in Delhi-NCR since 2018. Based on forecasts, the system provides warnings on severe air quality events. The DSS, which is likely to be introduced for the first time this year, is an extension of the existing system, said Gaurav Govardhan, scientist, IITM.

“In addition to forecasting severe air quality events, the DSS can tell us which regions could be responsible for the pollution – how much of the pollution is coming from Delhi and how much from nearby districts,” said Govardhan, who is part of the team that developed the system.

IITM began to develop DSS in February-March this year, with the Commission for Air Quality Management (CAQM) having stated a requirement for it, Govardhan said.

Apart from Delhi, data on pollutants will be collected from 19 nearby districts including Jhajjar, Sonipat, Gurgaon, Faridabad, Ghaziabad, Panipat, Rohtak, Gorakhpur, Rewari, Meerut, Bulandshahr and Alwar.

The data on PM 2.5 levels is collected from 43 stations of the Central Pollution Control Board (CPCB) and assimilated into the DSS and the air quality warning system. The forecast provided for the next five days will be based on numerical modeling, in addition to observational data from the stations.

Satellite imagery is also used in the model to check for instances of stubble burning. An emission inventory has been drawn from TERI to track regional distribution of emissions.

The DSS also provides ‘real-time source apportionment’ information – it will provide emission contributions of different sectors within Delhi. Eight sectors have been factored into the system to check their contributions to emissions – energy, residential, transport, waste burning, construction, road dust, industries (in Delhi and peripheral ones), and ‘others.’

“The data from DSS can then help make policy-level interventions. Different scenarios can be attempted. That is, if you reduce transport sector emissions, what sort of improvements can be made to reduce pollution. The objective is to help policy makers decide what choice to make,” Govardhan said.

This is the first time that source apportionment will be factored into the system to pinpoint the sources responsible for pollutants.

“The codes in the modeling system help segregate the pollutants as per contributions from various sectors and different districts. A ‘tracer’ approach, which is used in numerical modeling of atmospheric pollutants, is used in this case. A total of 470 ‘tracers’ are incorporated in the model, enabling source apportionment of PM 2.5,” Govardhan said.

The website, once officially launched, will be accessible to the public. “In addition to the source contributions and control strategies, it will be possible to create scenarios on the website – reducing pollution from certain sectors by a certain percentage to see what effect it will have on air quality,” Govardhan said.

The team at the institute will run the model and publish results on the website. “Final approval is awaited from the CAQM and the Ministry of Earth Sciences before we can go public with the website,” he added.

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