China's economic restructuring reduced emissions of polycyclic aromatic hydrocarbons (PAHs) in the post-global financial crisis era

Polycyclic aromatic hydrocarbons (PAHs) emissions driven by transboundary supply-chain activities across Chinese provinces are largely unknown. In this study, we comprehensively assessed the dynamics of production-, consumption-, and income-based PAHs emissions from individual Chinese provinces in China from 2007 to 2017. We also examined the critical supply-chain paths and socioeconomic drivers behind the changes in PAHs emissions and explored their correlations with China's economic restructuring during this period. We found that production-, consumption-, and income-based PAHs emissions have decreased to lower levels in 2017 (45.6, 36.2, and 40.1 kt, respectively) than those (52.8, 37.5, and 43.6 kt, respectively) in 2007. The dominant contributors of trade-driven PAHs emissions were located in the northern inland provinces with rich coal resources and the southeastern coastal provinces with dense populations and developed economies. China's economic restructuring reduced PAHs emissions in these provinces in the post-global financial crisis era, benefiting from improvements in emission intensity and trade structure. Concurrently, migrating energy- and emission-intensive industries into less affluent provinces (e.g., Xinjiang, Jiangxi, Henan, Anhui, and Yunnan) changed the roles of emission factors (from the demand side), primary input structure and energy mix (from the supply side) from driving down to driving up PAHs emissions. These changing drivers exerted a greater upward influence on PAHs emissions than the overall downward influence exerted by other drivers, thereby causing emissions outsourcing and leakage. This study explored the effects of economic structural transition on interprovincial trade-driven PAH emission transfer, offering valuable insights for policymakers to formulate policies for mitigating PAHs emissions.