With the accelerated growth of global trade, the shipping industry has experienced substantial expansion due to its reliability and cost-effectiveness in facilitating globalization. However, the environmental consequences of this rapid development, particularly pollution emissions, have garnered increasing attention. Sulfur dioxide has drawn more attention than other shipping pollutants due to its serious negative effects on health. America has three delimited emission control areas to limit sulfur emissions from ships and to enhance the quality of air in America’s coastal areas. This paper uses the difference in difference (DID) model to assess the sulfur emissions in the five busiest ports in America and check whether the emission control area (ECA) policy has a positive significant effect in decreasing the sulfur dioxide emission in the five busiest ports in America. The variables used for this study are sulfur emissions, gross domestic products, imports, exports, inflation rate as well as throughput for each of the five ports. The research results indicate that sulfur emission policies have no significant positive impact on ports other than the Port of Los Angeles, as many regulations have been developed to reduce the adverse effects of ship pollution emissions before the implementation of sulfur regulations.
Xiao et al. (Wed,) studied this question.