A new estimate suggests that land-based sources release 600 quadrillion microplastics into the atmosphere each year.
By KR Callaway edited by Claire Cameron
Microplastics travel by air and sea and appear even in remote areas.
Ben Stansall/Getty Images
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Microplastics are omnipresent, found everywhere on Earthfrom the Sahara Desert to patches of Arctic sea ice. Yet despite the ubiquity of these plastic particles, scientists have struggled to determine exactly how much there is in our atmosphere.
Now a new estimate published in Nature suggests that terrestrial sources releasing approximately 600 quadrillion (600,000,000,000,000,000) microplastic particles into the atmosphere each year, around 20 times more than the number of particles brought by the oceans (around 26 quadrillion).
The median concentration of microplastics is 0.08 particles per cubic meter (m3) on earth and 0.003 particles per m3 above the sea, according to the study.
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These estimates are between 100 and 10,000 times lower than previous accountings of atmospheric microplastics – a gap that, according to the researchers behind the new study, highlights the need for better overall measurements of these pollutants.
“We knew that the uncertainties in existing emissions estimates were very large,” says Andreas Stohl, lead author of the study and an atmospheric scientist at the University of Vienna. “They’re even still large after our study, but we could at least reduce the range of uncertainty, particularly in the importance of land versus ocean emissions.”
A microplastic is a plastic particle whose size is between one micron and five millimeters. Easily swept by wind and carried long distances by water, these tiny particles are also extremely difficult to detect and almost impossible to remove from the environment.
Previous estimates have focused on accounting for microplastics generated by human activity or directly measuring their concentration in the air in a given area. But these measurements vary widely: along the southeast coast of China, for example, atmospheric microplastics estimates varied from 0.004 to 190 particles per m3. To try to get a more global estimate, Stohl and his team compiled 2,782 measurements collected at 283 sites around the world.
The researchers hope the findings will serve as a basis for future studies of global microplastic levels, including new measurements that can account for even smaller particles than they did.
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