New research has concluded that the presence of microplastics in the air may be two to six times greater than previously thought.
The air around cities may contain microscopic plastic pollution levels much higher than scientists previously believed, according to new research in the journal Science Advances.
Using an innovative detection method, researchers found concentrations of plastic particles suspended in the air orders of magnitude higher than previous estimateswhich raises new concerns about the role of plastics on the climate, ecosystems and human health.
Over the past two decades, scientists have identified microplastics — particles smaller than 5 millimeters — and even smaller nanoplastics as an emerging global pollutant. These particles have already been detected throughout the Earth system, from oceans and soils to living organisms.
However, the atmosphere remains the least understood component of the global plastic cycle, mainly because existing tools have difficulty reliably detecting microscopic and nanometer-sized particles.
To fill this gap, a research team from the Institute of Terrestrial Environment of the Chinese Academy of Sciences has developed a new semi-automated analytical approach to measure non-ar plastic particles. The method tracks plastics in multiple atmospheric pathways, including airborne particles, dust, rain, snow and resuspension of dust.
The researchers tested their system in two major Chinese cities, Guangzhou and Xi’an. Their approach uses computer-controlled scanning electron microscopy, significantly reducing human subjectivity compared to traditional visual identification techniques. This allowed the team to detect plastic particles more consistently and at much smaller sizes than previous methods.
The results were impressive. Plastic concentrations measured in total suspended particles and deposited dust were two to six orders of magnitude higher to levels reported in previous studies that relied on manual analysis methods such as μ-FTIR or μ-Raman spectroscopy. The findings suggest that plastic air pollution has been drastically underestimated.
The study also showed that the movement and distribution of microplastics and nanoplastics varied widely along atmospheric trajectories, spanning differences of two to five orders of magnitude. Much of this variation was associated with street dust being thrown back into the air and wet deposition processes, such as rain and snow. As the plastics traveled through the atmosphere, the particles tended to clump together, leading to more diverse mixtures in deposited samples than in suspended aerosols.
Notably, the research marks the first time that nanoplastics have been used. By clarifying how plastics move, transform and eventually deposit in the atmosphere, the study offers crucial information about their potential impacts on climate systems, ecosystems and human health.
