Microplastics and Nanoplastics in the Atmosphere: Revealing an Invisible Dimension of Global Plastic Pollution
Over the past two decades, microplastics (MPs) and nanoplastics (NPs) have emerged as a major environmental concern, transforming our understanding of plastic pollution from a largely visible, ocean-centered problem into a pervasive, planet-wide challenge. Once thought to accumulate primarily in marine environments, plastic particles are now known to circulate through all major Earth systems—the atmosphere, hydrosphere, lithosphere, and biosphere. Their presence in air, water, soil, and living organisms underscores their role as a novel and persistent component of modern biogeochemical cycles. Despite growing awareness, fundamental questions remain unanswered, particularly regarding the abundance, sources, transport pathways, and ultimate fate of atmospheric plastics.
Atmospheric microplastics and nanoplastics represent one of the least understood aspects of the global plastic cycle. Unlike larger plastic debris, these tiny particles can remain suspended in the air, travel long distances, and interact with climatic and ecological processes in ways that are only beginning to be explored. Their small size makes them exceptionally difficult to detect and quantify, especially at the nanoscale. As a result, existing estimates of atmospheric plastic pollution have likely underestimated both its scale and its significance. Addressing these limitations requires new analytical tools capable of capturing the full size spectrum of plastic particles in complex environmental samples.
In response to these challenges, researchers from the Institute of Earth Environment of the Chinese Academy of Sciences (IEECAS) developed a semi-automated microanalytical technique designed specifically to detect and quantify plastic particles in the atmosphere. This innovative approach represents a major step forward in environmental monitoring, as it enables consistent and objective analysis across a wide range of particle sizes. By combining computer-controlled scanning electron microscopy with automated data processing, the method reduces human bias inherent in traditional visual identification techniques and significantly improves detection reliability.
The research team applied this new method in two major Chinese cities, Guangzhou and Xi’an, which differ in climate, urban structure, and atmospheric conditions. By analyzing multiple atmospheric pathways—including total suspended particulates (TSP), dustfall, rain, snow, and resuspended road dust—the researchers were able to trace how plastics move through the urban atmosphere. This comprehensive sampling strategy allowed for a detailed examination of both airborne plastics and those deposited through dry and wet processes, offering a more complete picture of atmospheric plastic dynamics.
The findings revealed plastic concentrations that were dramatically higher than those reported in earlier studies. Specifically, the levels of microplastics and nanoplastics detected in TSP and dustfall fluxes were two to six orders of magnitude greater than previous estimates obtained using manual scanning electron microscopy, micro–Fourier transform infrared spectroscopy (μ-FTIR), or micro-Raman spectroscopy. These results suggest that conventional methods have substantially underestimated the true abundance of atmospheric plastics, particularly at smaller particle sizes that are difficult to identify visually.
The study also found that the movement of plastic particles across different atmospheric pathways varied widely, spanning two to five orders of magnitude. Road dust resuspension emerged as a major contributor to airborne plastics, highlighting the role of urban traffic and surface abrasion in generating and redistributing plastic particles. Wet deposition processes, including rainfall and snowfall, were also identified as key mechanisms for removing plastics from the atmosphere. Together, these pathways shape the residence time, transport distance, and eventual deposition of plastics in terrestrial and aquatic environments.
Interestingly, the researchers observed that plastic particles collected from deposition samples—such as rain and dustfall—were more unevenly mixed than those found in aerosols or resuspended dust. This pattern suggests that as plastics travel through the atmosphere, they tend to aggregate or clump together, increasing their likelihood of being removed by gravitational settling or precipitation. Such transformations during atmospheric transport may influence how plastics interact with other airborne particles, pollutants, and cloud-forming processes.
One of the most significant achievements of the study was the detection of nanoplastics as small as 200 nanometers within complex environmental samples. This marks the first time particles of this size have been quantitatively identified in the atmosphere under real-world conditions. Nanoplastics are of particular concern because their small size allows them to penetrate deep into the human respiratory system and potentially enter the bloodstream. Their high surface area also makes them more chemically reactive, increasing the likelihood that they can carry toxic substances or interact with biological tissues.
By providing a detailed quantitative assessment of atmospheric microplastics and nanoplastics, the study fills a critical knowledge gap in the global plastic cycle. The atmosphere has long been considered a secondary pathway for plastic transport compared to oceans and rivers, but these findings challenge that assumption. Instead, the atmosphere emerges as a dynamic and influential reservoir that connects land, water, and living systems through long-range transport and deposition.
The implications of these findings extend beyond pollution monitoring. Atmospheric plastics may influence climate processes by interacting with radiation, cloud formation, and atmospheric chemistry. They may also affect ecosystem health by depositing plastics into remote environments, including agricultural soils, forests, and freshwater systems. For humans, inhalation exposure to microplastics and nanoplastics raises important questions about respiratory health, inflammation, and long-term disease risk.
In conclusion, this study represents a major advancement in the detection and understanding of atmospheric plastic pollution. By introducing a semi-automated, high-resolution analytical method, the researchers have revealed that plastics in the air are far more abundant and complex than previously recognized. Their work highlights the atmosphere as a critical, yet underappreciated, component of the global plastic cycle and underscores the urgent need for improved monitoring, standardized methodologies, and interdisciplinary research. As plastic production continues to rise worldwide, understanding how these particles move through the air—and how they affect climate, ecosystems, and human health—will be essential for developing effective environmental policies and mitigation strategies.
Source: Chinese Academy of Sciences Headquarters
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