While Mumbai has focused on controlling local sources of air pollution, a new pan-India study suggests this approach alone may not be enough to improve the city’s air quality, especially during the winter months when pollution spikes due to both internal and external factors.
The study proposes that Mumbai be integrated into a coastal airshed which includes all its satellite cities to effectively address and manage, urban and non-urban (outside the city administrative region) emission sources. In this process, the regional airshed will foster cooperation among the Urban Local Bodies, which are influencing each other's air quality.
The peer-reviewed study, Designating Airsheds in India for Urban and Regional Air Quality Management, published in MDPI’s Air journal, recommends dividing India into 15 regional airsheds, each tailored to the specific climatic and pollution patterns of its region.
This approach, the study indicates, could significantly improve Mumbai's air quality by tackling pollution from both inside and outside the city.
What Is an Airshed?
An airshed is a geographic area where air pollution is measured and managed as a whole. It recognises that air pollution doesn’t stop at city or state borders—pollutants can travel across regions. As a result, effective pollution management requires cooperation between cities, states, and even neighbouring countries.
Why Mumbai Needs a Regional Airshed?
Mumbai’s air quality worsens significantly during the winter months, driven by a combination of meteorological factors and pollution sources from both within and beyond the city limits. According to the World Air Quality Report 2023, Mumbai’s PM2.5 levels rose by 23% in January 2023 compared to the same period in 2022, making it one of the worst-affected cities globally during the winter season.
Sarath Guttikunda, lead author of the study and founder of UrbanEmissions.info, stated: “Mumbai is a significant regional contributor to air pollution. While the city can gain considerable benefits from managing pollution within its immediate surroundings, this relationship is reciprocal; the surrounding satellite cities also stand to benefit greatly from efforts to control emissions originating in Mumbai. Coordinated management across Mumbai and its neighboring areas could create a positive feedback loop, enhancing air quality and health outcomes for the entire Western airshed,” he added.
The 15 Crucial Airsheds Suggested by the Study:
The study proposes dividing India into 15 regional airsheds, each tailored to address the distinct climatic and pollution patterns of that region. These airsheds include:
Himalayas (2 airsheds)
Gangetic Plains (4 airsheds)
Plateaus (4 airsheds)
Arid/Desert (1 airshed)
Coastal Plains (3 airsheds)
Islands (1 airshed)
The study’s methodology involved analysing pollution levels and emission patterns across India to define airsheds that include both urban and rural areas. As of 2022, only four of India’s regional airsheds complied with annual air quality standards for PM2.5, compared to 1998, when only four exceeded these limits.
The study identified 11 airsheds as crucial for overall air quality management, with the Indo-Gangetic Plains (IGP) and the plateau region between the Eastern and Western Ghats emerging as priority areas. The IGP alone, which accounts for 16% of India’s landmass and 41% of its population, bears a high pollution burden due to extensive industrial activity, agriculture, and energy production.
“While regions like the IGP bear the brunt of industrial and agricultural pollution, contrary to popular belief, coastal cities like Mumbai have also witnessed a spike in pollution levels, particularly in winter, despite the benefits of land-sea breezes.In an urban regional airshed, the participating members would include a broad institutional setup, involving urban local bodies (ULBs), state officials, ministries, and regional stakeholders. This larger collaboration is essential to addressing shared air quality issues in coastal cities like Mumbai,” Guttikunda said.
Learning from the United States Model
The study concludes by recommending the establishment of a national system that integrates both regional and urban airsheds under a centralised air quality management framework. This system, similar to the US Environmental Protection Agency’s (USEPA) approach, would unify data collection, monitoring, and pollution control measures across regions.
“A centralised system would enable better coordination between cities, states, and airsheds, helping us monitor progress and ensure that everyone is working towards the same clean air goals,” Guttikunda said. “Air pollution isn’t just an environmental challenge—it’s a public health crisis. By creating a coordinated airshed approach, we can make significant progress in improving the air quality for cities and rural areas across India,” he added.
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