Inequality of pollutant discharge in an urban agglomeration and nonurban agglomeration—evidence from a new Theil-DEA model

Under the goal of carbon neutralization, the prevention and control of pollution emissions are very meaningful. Different levels of urban economic development correspond to different pollutant discharges. An assessment of pollution inequality among cities can quantitatively explain regional differences in pollution treatment. This paper proposes a new paradigm to measure pollution inequality within the Yangtze River Delta Economic Zone of China and aims to compare the inequality of pollutant discharge of urban agglomerations and nonurban agglomerations from 2001 to 2017. The findings reveal that the overall pollutant discharge shows a slight upward trend and gradually changes from a “two polarization” distribution in 2001 to a “centralized” distribution in 2017. However, the inequality of pollutant discharge declines during this period, whereby the pattern of the within-group inequality component is similar to the overall inequality, while the inequality of nonurban agglomeration pollution is more severe than that of urban agglomeration pollution. Further decomposition indicates that the difference in pollution intensity is the most critical factor leading to the inequality of pollution discharge, and reducing the gap in energy intensity is the most rapid way to reduce the inequality of pollution discharge. To measure the total driving force that leads to their inequality and to predict the degree of inequality of pollutant discharge, we use a new Theil-DEA model. Based on the empirical results, we anticipate that the imbalance of pollutant discharge will either temporarily maintain the status quo or worsen. Finally, we briefly discuss policy recommendations and special issues.