Measuring atmospheric microplastic composition and concentration from an uncrewed aerial system

Abstract Airborne microplastic (MP) particles are transported through the atmosphere, yet direct measurements at altitude remain scarce. We developed a novel uncrewed aerial system (UAS)-based method for in situ MP sampling near the air-sea/air-land interface or along the vertical axis within and above the atmospheric boundary layer, motivated by evidence that sea spray injects MPs into the marine boundary layer and by documented long-range MP transport. In this proof-of-concept study, we deployed the UAS at 80–100 m above ground level in Colorado, USA, during fall 2024, collecting particles larger than 1 µm at two sites with high anthropogenic activity using an environmental cyclone sampler. Plastic-like particles were isolated, counted by optical microscopy, and identified by Raman microscopy with automated spectral analysis (OpenSpecy). MPs were detected at both sites, with plastic-like particle concentrations of 10.09 ± 4.13 m⁻³ for particles 3–10 µm. These estimates should be considered conservative upper bounds. Hetero-aggregates dominated the samples, consistent with traffic-related material, with compositional differences between sites reflecting local human activity. This proof of concept demonstrates the feasibility of UAS-based atmospheric MP sampling and establishes a framework adaptable for ocean-surface, high-altitude, and remote environment monitoring.