In 2018, global plastic production amounted to 359 million tonnes, leading to increased concern over plastic pollution in freshwater, marine, and terrestrial ecosystems. One significant contributor to plastic pollution is road traffic emissions, specifically through tyre wear and brake wear, but also from sources such as polymer-modified bitumen used for road pavement or road marking paint.
In their paper, Evangeliou et al present global simulations of the atmospheric transport of microplastic particles produced by road traffic. The simulations revealed that emissions of road microplastics are concentrated where vehicle densities are highest, in the eastern US, Northern Europe and large urbanized areas of Eastern China, Middle East and Latin America. Smaller particles (PM2.5) are dispersed more widely than larger ones (PM10), with PM10 being deposited mainly close to the hotspot emission regions.
The simulations showed that the road microplastic particles were transported to remote regions. About 34% of the emitted coarse tyre wear particles and 30% of the emitted coarse brake wear particles (100 kt per year and 40 kt per year respectively) were deposited in the World Ocean. They suggest that the light-absorbing properties of the particles in the Arctic may cause accelerated warming and melting of the cryosphere (where water is frozen in solid form).
Read the full paper:
Evangeliou, N., Grythe, H., Klimont, Z., Heyes, C., Eckhardt, S., Lopez-Aparicio, S. and Stohl, A., 2020. Atmospheric transport is a major pathway of microplastics to remote regions. Nature communications, 11 3381. https://www.nature.com/articles/s41467-020-17201-9