Improving environmental performance has been widely regarded as a key action to promote environmental sustainability. However, in most environmental performance models, the optimization pathways are pre-determined, neglecting the heterogeneity of the optimization pathways inherent in different producers, which can lead to a potential risk of distorting the results of environmental performance and generating misleading policy implications. This study reveals how endogenous optimization pathways for improving environmental performance can be identified. We first develop a distance function with endogenous direction to identify the endogenous optimization pathways for improving environmental performance and then propose an environmental performance index based on the identified endogenous optimization pathways. We apply our approach to a sample of 101 Chinese cities by considering two major pollutants (i.e., SO₂ and NOx emissions). It is found that our approach can capture the heterogeneity of the optimization pathways across different cities and pollutants well. A majority of cities prefer to improve their environmental performance by reducing NO_x emissions rather than reducing SO₂ emissions.

改善环境绩效已被广泛认为是促进环境可持续性的关键行动。然而，在大多数环境绩效模型中，优化路径是预先确定的，忽略了不同生产者固有的优化路径的异质性，这可能导致扭曲环境绩效结果和产生误导性政策影响的潜在风险。本研究揭示了如何确定改善环境绩效的内生优化途径。我们首先开发一个具有内生方向的距离函数来识别改善环境绩效的内生优化路径，然后基于确定的内生优化路径提出环境绩效指标。₂和 NOx 排放）。发现我们的方法可以很好地捕捉不同城市和污染物的优化路径的异质性。大多数城市更愿意通过减少 NO _x排放而不是减少 SO ₂排放来改善其环境绩效。