Visualizing invisible NOx emissions and remodeling policy requirements within bidirectional supply-demand control

Substantial anthropogenic nitrogen oxides (NOx) emissions have attracted public concern because of its negative impacts on human health and eco-environment and become one of the major air pollutants in China during 14th National Five-Year Plan (FYP). Existing studies have made great contributions to the end-of-pipe NOx treatment but the evaluations of “invisible” emissions due to primary supply and final demand embedded within the whole supply chain are incomplete and the corresponding mitigation mechanisms remain unknown. Under the background of synergistic control for greenhouse gases and air pollution, the comprehensive rather than unilateral NOx control measures are necessary for achieving the maximization of emission reduction benefits. In this study, the environmentally extended Leontief- and Ghosh-based input-output sub-models were constructed and weighted average structural decomposition analysis technique was incorporated into the model framework for quantifying and decomposing the both demand-driven and supply-push NOx emissions of the whole socioeconomic industrial system of China during 2007–2017. Here we show that the total NOx emissions over China presented inverted U-shaped trend with the change rates of 19.6% and 16.9% during 2007–2017, and over 40% and 70% of this are embedded within the intersectoral supply-push and demand-driven intersectoral NOx flows. Construction sector contributed more than average 35% of national consumption-based NOx emissions, which mainly attributed to high-NOx-intensive fixed capital formation. Meanwhile, comprehensive control is essential for heavy industry sector due to its high proportion of national NOx emissions under all of the three perspectives. Air pollution control is a vital but long-term project, the obtained results and policy implications of this study could not only promote the NOx emission reduction from supply-demand perspective, but also provide more holistic and insightful enlightenment for decision-makers to consider the air quality improvement strategies from a systemic and comprehensive perspective.