“Studies that have estimated the concentration of microplastics in the atmosphere show high levels of variability, with results ranging across several orders of magnitude. And studies that have taken measurements from a region in the western United States have been used to infer global emissions.

Evangelou and her team aimed to get a better handle on microplastic concentrations by compiling two sets of existing studies — those that estimated global microplastic emissions, and those that measured the particles found in environmental samples. They then used the second set to assess the validity of the first.

The researchers fed the estimated emissions data into a computer simulation of how the atmosphere transports pollutants. The simulation gave predictions of the concentrations of microparticles that would be found across the globe. But the predicted amounts did not match those found in samples at 283 different locations worldwide.

The difference was stark — in some cases, the microplastic measurements from environmental samples were orders of magnitude smaller than the models predicted. The team also estimated that 27 times more microplastic particles are emitted from activities on land than from the ocean.”

From Nature.