 The study shows that there is a large knowledge gap regarding the occurrence and burden of airborne microplastics, MPs, in the marine boundary layer, which hinders comprehensive modelling of their global atmospheric transport. The study presents inaugural measurements of MPs concentrations over the Southern Ocean and interior Antarctica and finds that MPs fibers are transported more efficiently than MPs fragments along the transect, with the transport dynamics of MPs generally similar to those of non-plastic particles. Morphology is found to be the dominant factor influencing the hemispheric transport of MPs to remote and toxic regions, highlighting the importance of long-range atmospheric transport in MPs cycling dynamics in the environment. This article was authored by Chiching Chen, Guidausha, Laura E. Reville, and others.