This SOLAS webinar will focus on microplastics at the ocean surface and in the lower atmosphere, with an emphasis on analytical approaches and measurement challenges. It will discuss current methods, their limitations, and the difficulties of reliably identifying and quantifying microplastics in complex environmental samples. The seminar will combine an overview of analytical challenges with initial insights from SOLAS-related measurements, followed by a broader perspective that links these findings to ongoing community efforts. Attention will be given to how current SOLAS and SCOR activities are working toward greater consistency and coordination in this field.