How much of TRWP makes its way to the ocean?
Scientifically validated (peer-reviewed) research that verified computational modeling with field sampling found that 2-5% of all tire and road wear particles (TRWP) emitted make it to a marine estuary and a small fraction is released into the air (Unice et al., 2019a, b).
In recent years, several studies have tried to estimate the quantities of TRWP present in oceans. However, many of these studies (IUCN 2017, UNEP 2018, PEW 2020, Earth Action 2021, OECD 2022) have reported wide-ranging values for microplastic sources, as summarized in a recent publication (Earth Action 2024). This high variability is due to different assumptions and models used in each report, making it extremely difficult to correctly interpret the results.
Some reports have tried to estimate the quantity of different possible sources of microplastic type and highlighted that paint might be the largest source of primary microplastic leakage into the ocean and waterways (Earth Action 2021).
Considering all the above, it is evident that additional research is needed to further scientific understanding of the topic and to guide future actions.
