Plastic waste leakage into the ocean and the environment has become a global issue, so in order to reduce plastic waste on a global scale, it is necessary to share scientific knowledge such as marine plastic litter distribution with countries around the world. In this article, we introduce the Atlas of Ocean Microplastic (AOMI), an international database on ocean surface microplastics that the Ministry of the Environment has developed and released to encourage data utilization, with the aim of promoting more effective plastic pollution countermeasures.

Plastic waste leakage into the ocean and the environment has become a global issue.
 It was a critical topic at the G7 Summit in Elmau, Germany in 2015 and the World Economic Forum in 2016, resulting in strengthened domestic legislation in various countries. At the G20 Osaka Summit in 2019 hosted by Japan, the "Osaka Blue Ocean Vision" was shared, aiming at reducing additional marine plastic litter to zero by 2050.
At the G7 Hiroshima Summit in 2023, participants ambitiously committed to eliminating additional plastic pollution by an 2040, ten years earlier than the G20 goal. While measures are being discussed, no internationally agreed-upon figures exist for the amount of plastic leaked into the environment.
To reduce this waste worldwide, the sharing of scientific insights, such as regarding plastic distribution status, that form the basis of global countermeasures is necessary.
Against this backdrop, the G7 Summit in 2015 prioritized the harmonization and standardization of monitoring methods.
At an international workshop, a follow-up to the summit, Japan made proposals to take the leading role in efforts to standardize and harmonize monitoring methods on microplastics in the ocean. Additionally, the “G20 Implementation Framework for Actions on Marine Plastic Litter,” adopted at the 2019 G20 Ministerial Meeting on Energy Transitions and Global Environment for Sustainable Growth, also called for promoting harmonized monitoring methods. At the follow-up meeting of the Framework held thereafter, Japan proposed taking the lead in harmonizing monitoring methods and data compilation, and this proposal was agreed upon¹.

As mentioned earlier, accumulating comparable data is crucial for implementing effective measures. However, methods used to research ocean surface microplastics varied according to purpose, making data comparison difficult.
In response, the Ministry of the Environment conducted a demonstration project comparing sampling and analysis methods. After discussions with domestic and international experts, they released the first edition of the Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods² in May 2019. These guidelines were revised in 2020 and 2023.

Although the guidelines mentioned above made it possible to collect comparable survey data on ocean surface microplastics, global monitoring data has not yet been organized into a comparable state. In response, and with input from experts, the Ministry of the Environment built the Atlas of Ocean Microplastic³ (AOMI, meaning "Blue Ocean" in Japanese), a mapping database for ocean surface plastic litter and released it in May 2024.
AOMI gathers monitoring data on ocean surface microplastics from researchers, institutions, and governments worldwide and provides 2D maps showing particle density distribution and survey locations. Researcher provided data undergoes a quality control check, including error checks, and is stored as comparable data following the aforementioned guidelines released by the Ministry of the Environment. The stored data is provided as downloadable open data, along with 2D maps created from the data (Figure).
AOMI's worldwide publication of monitoring data helps clarify regions with insufficient data. This is expected to promote monitoring, especially in data-deficient regions, in the future. Additionally, since AOMI accumulates time-series data on the presence of microplastics in marine areas, its use is anticipated as a tool for verifying the effects of plastic pollution countermeasures. This environmental plastic concentration data is expected to be used as basic data on risks for future research and evaluation, such as exposure assessments of living organisms and risk assessments related to plastics. Furthermore, by widely distributing clear information on the distribution of plastics in the environment, AOMI contributes to raising awareness and understanding of marine plastic pollution.
As of December 2024, AOMI particularly lacks data from marine areas near Southeast Asia, Africa, and around South America. Accumulating data from these regions and encouraging the use of the accumulated data is crucial to promoting AOMI's spread. Moreover, in addition to the database constructed by the United Nations Environment Programme Global Partnership on Plastic Pollution and Marine Litter (UNEP GPML), it is necessary to collaborate with other databases built in other countries and regions, such as Europe's European Marine Observation and Data Network (EMODnet) and the US's NOAA National Centers for Environmental Information (NCEI). The Ministry of the Environment has already been collaborating with relevant organizations, including the aforementioned ones, and has conducted monitoring implementation support in regions like Southeast Asia. It plans to continue taking various opportunities to promote awareness and expand the use of AOMI.

1. Ministry of the Environment: Harmonized Monitoring and Data Compilation of Marine Plastic Litter https://www.env.go.jp/water/post_76.html
2. Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods, 2023
https://www.env.go.jp/content/000170502.pdf
3. Atlas of Ocean Microplastics（AOMI） https://aomi.env.go.jp/