Impact of IMO Sulfur Regulations on Air Quality in Busan, Republic of Korea

In this study, we investigate the air quality improvement effect in Busan, the largest port city in South Korea, caused by the implementation of International Maritime Organization (IMO) sulfur regulations. Currently, the Korean government is struggling with problems related to PM2.5, and ships are one of the major sources of PM2.5 generation in South Korea. Therefore, we tried to estimate how much the PM2.5 levels in South Korea could be improved via low-sulfur regulation. According to the Clean Air Quality Policy Support System (CAPSS; National Emission Inventory) in 2016, ship emissions in Busan accounted for 39%, 71%, and 39% of PM2.5, SO2, and NO2 emissions, respectively. To simulate the effect of the IMO’s 0.5 percent sulfur regulation, SOx and PM2.5 emissions from oil-fueled cargo ships were reduced. Via ship fuel regulation, the PM2.5 concentration was improved by up to 19% at a site near the port in 2020. In addition, in the case of sulfate, the reduction rate was higher on the downwind side of the Busan port and not near the port, which can be considered as the cause of advection and secondary formation. The PM2.5 contributions from ships to each of the sub-regions in Busan also decreased by an average of 47% because of IMO sulfur regulation. Although there were limitations in terms of emission estimations because of the application of low-sulfur regulation, we expect that the results of this paper can be used for additional PM2.5 improvement plans developed by the Korean government and by the local government as well