Many ships are switching to low sulfur fuel oil due to the global sulfur cap 2020. The switch to low sulfur fuel oil is expected to reduce not only SOx but also organic pollutants contained in PM. In this study, the emission characteristic of polycyclic aromatic hydrocarbons (PAHs), a type of organic pollutants contained in PM, was evaluated before and after the global sulfur cap 2020, by collecting PM emitted from a ship in operation. Among PAHs, the 27 compounds that have been drawing attention due to their impact on living organisms were measured. The main engine of the ship was a two-stroke marine diesel engine, and the ship was operated by using alternatively heavy fuel oil and low sulfur fuel oil (LSA oil). The engine load was increased stepwise from 25%, 50%, 75%, to 90%, and PM was collected at each load. As a result, the total emission of the 27 compounds was decreased due to switching to LSA oil, then the impact on the atmospheric environment was reduced. While, the 2 compounds, Pyrene and Benzo[a]anthracene, emission was increased. Lastly, the emission concentration of the 27 compounds decreased proportionately to the rise of the engine load for both cases using heavy fuel oil and LSA oil, while, there was also the part unique to a ship in operation.

In this study, we focused on terminologies expressing the analysis results of the Japan Transport Safety Board and conducted a combined analysis of quantitative and qualitative of investigation reports related to marine accidents and incidents caused by engine failures. The results show that machine failures as hardware factors tended to be classified as "high probable." The results also show that latent failures and active errors tended to be classified as "probable.", active errors appeared simultaneously with latent failures such as design flaw of a machine. The results also show that most of the latent failures were poor machine maintenance, decisions made by machine designers and ship managers were rare, and insufficient training was not observed in investigation reports. In addition, the results show that "Assertive" and "Almost certain" included not only the causes of the failure in accidents, but also everyday successes. Based on the results of the combined analysis of quantitative and qualitative, the authors considered four countermeasures from an academic standpoint against latent failures that have commonality and relevance in the marine engineering department. The first is to record maintenance sheet against poor machine maintenance. The second is engineering countermeasures by machine designers. The third is to enhance resilience of organization as a countermeasure for decision-making by managers. The fourth is to increase and ensure everyday success of training and education to enhance resilience engineering.