Impact of Ship Emission Control Area Policies on Port Air Quality—A Case Study of Ningbo Port, China

Abstract

The implementation effectiveness of ship emission control area (ECA) policies can be effectively evaluated using econometric models. However, existing studies mainly focus on changes in SO2 concentrations in the air. In order to comprehensively assess the impact of ECA policies on air quality, this study takes Ningbo Port in China as an example and uses a regression discontinuity (RD) model to analyze the influence of ship emissions around the wharf on concentrations of SO2, NO2, and particulate matter (PM) in the air. The results indicate that individual ships’ activities within the monitoring area (within 300 m) make a relatively small contribution to the concentration of SO2 in the air and do not form a significant breakpoint. However, there is a noticeable breakpoint in the concentration of NO2 around the monitoring point as the ship approaches. At the same time, the variation range of PM2.5 is significantly greater than that of PM10, which aligns with the characteristics of PM emitted by ships. The experimental results have passed three robustness tests, demonstrating that the current policy on ship ECAs has a positive limiting effect on SO2 emissions and, to some extent, reduces PM emissions. However, further reductions in ship emissions may require more restrictions in nitrogen oxide emissions.