Changes in industrial NOx emission efficiency in China: impacts of energy structure, industrial structure, and urbanization level on NOx emissions

Reducing nitrogen oxides (NOx) emissions is crucial for controlling combined pollution of particulate matter and ozone in China. Currently, there is limited research on the emission efficiency of the zone. This work evaluates the industrial NOx emission efficiencies of 30 provinces in China from 2012 to 2021 based on a three-stage SBM-DEA model, and analyzes the impacts of energy structure, industrial structure, and urbanization level on industrial NOx emission efficiencies, which can help to contribute to the realization of synergistic development between economic growth and environmental protection. The results reveal several key findings. Firstly, concerning emission efficiency, stage I and stage III exhibit overall efficiencies of 0.27 and 0.35, respectively, underscoring ample room for enhancing China's industrial NOx emission efficiency. The eastern regions exhibit higher emission efficiencies, with central and some eastern regions predominantly falling within the 0.2–0.4 range, while the majority of northeastern and western regions register efficiencies below 0.2. Secondly, the analysis demonstrates the substantial impact of external environmental factors on China's industrial NOx emission efficiency, often resulting in underestimation across most provinces. An increase in fossil energy consumption and a higher proportion of industrial structure can lead to a decrease in emission efficiency.