The impact of low-sulfur marine fuel policy on air pollution in global coastal cities

Abstract

Shipping emissions significantly contribute to the fallout of air pollutants in many coastal cities. Among these emissions, sulfur dioxide (SO₂) is a major concern because it not only causes acid rain and photochemical smog that seriously damages human health but also damages sensitive ecosystems around the world. The United Nations and many local governments have established regulatory schemes to reduce SO₂ by setting global regulations and emission control areas (ECAs) that would require the use of much cleaner marine fuel with lower sulfur content or equivalent SO₂ scrubber devices. By combining remote sensing with spatial econometric models, we find that SO₂ decreases with implementation of regulations on sulfur limits varied across the study areas. The emission control areas in North America and China can reduce the average sulfur dioxide concentration in coastal cities by about 3–5 %, but in the Baltic and North Seas, ECAs did not show a significant impact at the spatial average level. While the overall spatially averaged SO₂ changes were relatively small, port cities and offshore waters with frequent shipping activities experienced significantly larger reductions, ranging from 10 % to 28 %. In addition, setting a general cap on sulfur content may be a better way to curb air pollution in coastal cities. The Mediterranean region and China experienced more notable reductions in SO₂ concentrations, namely 6.4 % and 3.8 %, respectively, following the adoption of the global regulation.