Plastic in city air may be far more widespread than earlier studies found

Researchers using automated microscopy reported microplastics and nanoplastics in urban air at levels far higher than earlier visual methods indicated.

Scientists have detected microplastics and nanoplastics across the Earth system, and the atmosphere remains the least understood reservoir. Researchers at the Institute of Earth Environment of the Chinese Academy of Sciences developed a semi-automated microanalytical technique to measure plastics in air, deposition, and resuspended dust. They applied this system in Guangzhou and Xi'an and used computer-controlled scanning electron microscopy to reduce manual bias. The team reports detection of nanoplastics down to about 200 nm and much higher concentrations than earlier visual-identification studies. Key findings: - The new semi-automated method uses computer-controlled scanning electron microscopy to identify plastic particles in complex environmental samples, extending detection to approximately 200 nm. - Reported plastic concentrations in total suspended particulates and dustfall were 2–6 orders of magnitude higher than values from earlier visual identification methods. - Estimates of plastic movement varied widely across atmospheric pathways, with road dust resuspension and wet deposition driving large differences, and deposition samples showing more particle clumping. Summary: The study provides a more detailed quantitative picture of micro- and nanoplastics in the atmosphere for the sampled cities and reports detection at smaller sizes than before. Its results indicate earlier methods may have substantially underestimated airborne plastics and highlight variable transport and removal processes. Undetermined at this time.