Evaluation of the effect of Global Sulfur Cap 2020 on a Japanese inland sea area

The Global Sulfur Cap 2020 regulation requires a decrease in the sulfur content in the fuel oil used on ships from 3.5% to 0.5%. In this study, atmospheric sulfur dioxide (SO2), nitrogen oxide (NOx), and fine particulate matter concentrations were measured in the Seto Inland Sea, a congested sea area in Japan. A rapid decrease was observed in ship emission indices, such as SO2, vanadium (V), nickel (Ni), and the V/Ni ratio, at coastal monitoring stations, providing evidence of the implementation of this regulation. Onboard observations clearly revealed a decrease in maritime gaseous SO2 immediately after the regulation came into effect; similar changes were observed in the coastal areas from January to June in 2019-2020. Although continuous studies will be needed to distinguish the benefits of the regulation from those of other factors, these findings will be useful for policymakers when addressing atmospheric pollution issues in congested sea areas.

Automated summary

This study conducted measurements on ship emissions in the congested Seto Inland Sea in Japan and found that the implementation of the Global Sulfur Cap 2020 regulation led to a rapid decrease in ship emission indices. Onboard observations showed a significant decrease in maritime gaseous SO2 after the regulation came into effect, and similar changes were observed in coastal areas. These findings are important for policymakers in addressing atmospheric pollution issues in congested sea areas.