Researchers have discovered far higher levels of microplastics and nanoplastics in city air than previously estimated, highlighting the atmosphere as a key pathway for plastic pollution. Using a new automated technique, scientists in China measured these tiny particles in Guangzhou and Xi'an, revealing concentrations two to six orders of magnitude above earlier reports. Road dust and rainfall significantly influence how these plastics move through the air.
Over the past two decades, microplastics (MPs) and nanoplastics (NPs) have emerged as a major environmental concern, appearing in the atmosphere, hydrosphere, lithosphere, and biosphere. Despite their ubiquity, gaps persist in understanding their quantities, sources, transformations, and accumulation, particularly in the air where detection methods have been limited.
To address this, scientists from the Institute of Earth Environment of the Chinese Academy of Sciences developed a semi-automated microanalytical technique. This method employs computer-controlled scanning electron microscopy to quantify plastic particles consistently across a wide size range, minimizing human bias compared to manual approaches like SEM-EDX, μ-FTIR, or μ-Raman.
The team tested the technique in the Chinese cities of Guangzhou and Xi'an, analyzing total suspended particulates (TSP), dustfall fluxes, and other atmospheric pathways. Their findings showed plastic levels in TSP and dustfall to be two to six orders of magnitude higher than prior visual identification studies suggested, indicating significant underestimation in earlier research.
Movement of MPs and NPs varied by two to five orders of magnitude across pathways, primarily driven by road dust resuspension and wet deposition from rain and snow. Samples from deposition exhibited more clumped plastic particles than aerosols or resuspended dust, suggesting aggregation and removal during atmospheric transport.
Notably, the study detected nanoplastics as small as 200 nanometers in complex environmental samples for the first time. These insights into atmospheric plastics' dynamics provide a clearer view of their role in the global plastic cycle, with implications for climate processes, ecosystems, and human health.
The research, led by Tafeng Hu and colleagues, was published in Science Advances on January 7, 2026.
