An airshed is a geographical area where local topography and meteorology limit the dispersion of pollutants away from the area. Research and practice has shown that regulating pollution by taking into account airsheds, rather the arbitrary boundaries of cities and towns, can be a cost-effective way of fighting pollution.

Managing air pollution by taking into account the airsheds has done successfully in Europe and China, whose capital was once as synonymous with smog as New Delhi, India, is today. Beijing’s air is now cleaner chiefly thanks to the creation in 2013 of a powerful airshed-wide authority responsible for the capital, the city of Tianjin and 26 adjacent prefectures. In 2017 pm2.5 levels in Beijing were half those of the previous year.

India is trying to follow this example in and around Delhi. In 2021 it launched a pollution-control agency, called the Commission for Air Quality Management, with responsibility for a 55,000-square-km area, encompassing the capital and parts of Haryana, Rajasthan and Uttar Pradesh… Yet a decisive way to deal with air pollution in India will require a major expansion of this approach, according to the World  Bank.

The World Bank has identified six regional airsheds of South Asia. They are vast areas, covering multiple urban, provincial and national jurisdictions. Significantly, four of the six cross national borders. One stretches from eastern Iran into western Afghanistan and southern Pakistan; another covers much of northern India and western Bangladesh. According to the World Bank’s modelling, the more coordinated the pollution controls adopted in these airsheds, the more cost-effective and beneficial they would be.

The ideal scenario, it suggests, would be for authorities within a given airshed to co-operate, across national borders, on data-sharing and policy formulation, while each working towards a locally determined target. This would allow them to prioritize relatively easy or low-cost forms of pollution control—such as regulating brick kilns—over more difficult or expensive sorts, such as closing coal-fired power stations. The World Bank reckons that in this scenario South Asian life expectancies would rise, infant mortality would drop and health-care expenditure would fall. For a cost of $5.7bn, it estimates the approach could bring economic benefits worth $52.5bn by 2030.

The idea of Bangladesh, India and Pakistan—let alone Afghanistan and Iran—working together to such an extent… might almost seem absurd. South Asia is one of the most unneighborly, least-integrated regions in the world. It is haunted by a history of war and mutual suspicion. Its cross-border linkages are meagre. Trade within the region is just 5% of its members’ total trade…

Excerpts from, South Asia’s Filthy Air: Choked and Gasping, Economist, Feb. 18, 2023.