Sources and flows of China's virtual SO2 emission transfers embodied in interprovincial trade: A multiregional input–output analysis

China faces immense difficulties caused by its domestic regional air pollution caused by atmospheric diffusion of pollutants across administrative boundaries. Because of the closer interregional economic connections that have formed, in this study we focus on the virtual flows of pollutants embodied in interprovincial trade. We compared two methods, embodied emissions in bilateral trade (EEBT) and the multiregional input–output (MRIO) model, to determine emission flows for 2002 and 2007 and found that the results between these two approaches differed significantly, particularly for the year 2007. This indicates that the choice of the accounting method has obvious impacts on subsequent decisions. Further analysis based on the MRIO method, which captures the complete interregional supply chains and is more applicable to consumption-based studies, showed that the embodied SO2 emissions in interprovincial trade accounted for 27.58% of the total SO2 emissions in China in 2002 and 35.25% in 2007. Inner Mongolia, Shanxi, and Guizhou were the major embodied emission-exporting regions, with sources mainly from the electricity, nonmetal mineral production, chemicals, and metal smelting sectors. The exported emissions mainly ended up in rich provinces, including Beijing, Tianjin, Shanghai, and Guangdong, due to those provinces' final demands for products of the construction, food production, and transport equipment manufacturing sectors. Furthermore, rich provinces were net importers in interprovincial trade, with a pollution terms of trade value less than one. The results yield important implications for China's air pollution controls: emission reduction tasks should be reasonably distributed among provinces to prevent developed provinces from outsourcing more pollution emissions to less developed provinces through interprovincial trade; regulation of consumption in developed provinces would help to control national pollution; financial and technical support for pollution control should favor the less developed regions.