🔬 Microplastic levels in the atmosphere much lower than previously thought

• New estimates show that the amount of atmospheric microplastics is 100 to 10,000 times lower than researchers previously calculated.
• The study compiled 2,782 measurements from 283 locations worldwide to create a reliable global baseline.
• The researchers' model aligns well with actual observations of microplastic concentrations in the atmosphere.

New global mapping yields lower figures

A new study published in Nature shows that the amount of microplastic particles in Earth's atmosphere is significantly lower than researchers previously estimated. The new calculations are between 100 and 10,000 times below previous estimates. The difference is due to the research team using a new method where they compared model simulations with actual measurements from around the world.

According to Andreas Stohl, senior author of the study and atmospheric scientist at the University of Vienna, the uncertainties in existing emission estimates were very large. Uncertainties still remain after the study, but the research team was able to at least narrow down the uncertainty range. This is especially true when it comes to the importance of land-based versus ocean-based emissions.

Land-based emissions dominate

According to the study, land-based sources release approximately 600 quadrillion microplastic particles into the atmosphere every year. Ocean-based sources contribute around 26 quadrillion particles annually. This makes land-based emissions roughly 20 times larger than ocean-based ones.

The median concentration of microplastics is 0.08 particles per cubic meter over land and 0.003 particles per cubic meter over sea. The concentration over land is therefore 27 times higher than over the ocean.

How microplastics are defined

A microplastic particle is any plastic particle with a size between one micron and five millimeters. These small particles can easily be swept up by wind and transported long distances by water. They are difficult to detect and almost impossible to remove from the environment.

Microplastics are found everywhere on Earth. The particles have been found in the Sahara Desert and in Arctic sea ice. Despite this spread, researchers have previously struggled to determine exactly how many particles are in the atmosphere.

Large variations in previous measurements

Previous estimates have focused on counting microplastics generated by human activity or directly measuring the concentration in the air at specific locations. But these measurements have varied widely. Along the southeastern coast of China, atmospheric microplastic estimates have ranged between 0.004 and 190 particles per cubic meter.

To arrive at a more reliable global estimate, Stohl and his team compiled 2,782 measurements collected at 283 locations worldwide. The research team hopes the findings will serve as a baseline for future studies of global microplastic levels. Future measurements will also be able to include even smaller particles than the current study could measure.

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