Impact assessment of IMO's sulfur content limits: a case study at latin America's largest grain port

The world ocean fleet consumes around 4.3 million barrels of heavy fuel oil (HFO) daily, releasing large amounts of sulfur-enriched gaseous and particulate pollutants into the atmosphere. The International Maritime Organization (IMO) has set new sulfur content limit values for HFO under the Global Sulfur Cap 2020 (GSC-2020) program to reduce its environmental and public health impact. This study assesses the environmental benefits of the sulfur content limit values for heavy fuel oil set by the IMO on sulfur emissions, trace element concentrations, and ship related PM2.5 pollution at Paranagua, the largest grain port in Latin America. X-ray Fluorescence analysis revealed that the concentrations of vanadium (V) and nickel (Ni) in PM2.5 (i.e., finer particulate matter), which are prevalent trace elements in ship exhaust emissions, decreased significantly from 25.4 ng m(-3) and 5.8 ng m(-3) in 2019 to 3.5 ng m(-3) and 2.2 ng m(- 3) in 2020, respectively. The V/Ni ratio also changed from 4.3 in 2019 to 1.8 in 2020, suggesting significant changes in the signature of marine vessel emission. Sulfur emissions also decreased, with average concentrations of 2.0 mu g m(- 3) in 2019 and 1.2 mu g m(-3) in 2020. The primary PM2.5 concentration, attributed to ship emissions using V as a tracer, was reduced from similar to 80% in 2019 (mean = 35.8%) to less than 5% (mean = 4.9%) in 2020. Inhalation exposure to V and Ni in PM2.5 showed a decrease in the hazard quotient (HQ) and hazard index (HI) in 2020 compared to 2019, indicating potential health benefits. Our findings underscore the need for more robust international shipping policies prioritizing health objectives and reducing greenhouse gas emissions concurrently. Despite the significant health benefits associated with the implementation of low-sulfur fuels in global shipping, there remains a need for further investigation into the long-term effects of these fuels on air quality and human health.