Economic environmental imbalance in China - Inter-city air pollutant emission linkage in Beijing-Tianjin-Hebei (BTH) urban agglomeration.

Production fragmentation makes the air pollution policy no longer at the local scale but requires accounting more about embodied emissions cross-region through supply chains. Here, we map the consumption-driven NOx networks of Beijing-Tianjin-Hebei urban agglomeration (BTH) in China using the city-level multi-regional input-output model. The results show that the construction, service, and equipment manufacturing sectors in Beijing and Tianjin indirectly drive more than half of BTH NOx emissions (54%). Moreover, 75% of NOx flows in the supply chains are traded from cities with low efficiency (high intensity) to cities with high efficiency (low intensity), which reflects the economic environmental imbalance in BTH. Especially, for the metals smelting and pressing sector and nonmetal mineral products sector, there is a wider gap in emission intensity between production-oriented cities (1.03-4.43 Mt/million yuan) and consumer-oriented cities (0.08-0.45 Mt/million yuan), which leads to additional emissions of air pollutants to increase. At the same time, for the provinces in the south and north China, the role of BTH in the supply chain is different, which leads to an economic environmental imbalance between the north and the south. Synchronous outsourcing of production and technology is the key to solving the economic environmental imbalance. The consumption-oriented high-income cities are suggested to increase the financial and technical support to improve the efficiency of pollution control in production-oriented cities.