We know that microplastics are in the ground (and wind up in fruits and vegetables), in the water, and in our bodies. We've also learned microplastics actually fall from the sky.

In 2019 a scientific paper in Nature Geoscience reported that microplastics were falling from the sky over the Pyrenees Mountains in France—"a remote, pristine mountain catchment" with no obvious nearby sources. "We suggest that microplastics can reach and affect remote, sparsely inhabited areas through atmospheric transport," the paper reported.

This photo is actually of Yosemite, but you get the idea. Image: Jason Hogan on Unsplash

Deonie Allen, the paper's lead researcher, told National Geographic about similar studies done in cities. "If you go outside with a UV light, set at a wavelength of 400 nanometers, and shine it sideways you'll see all kinds of plastic particles in the air fluoresce," she said. "It's almost worse indoors. It's all a bit terrifying."

In 2020, Science reported that researchers had found "even the most isolated areas in the United States—national parks and national wilderness areas—accumulate microplastic particles after they are transported there by wind and rain:"

"They estimate that more than 1,000 metric tons per year fall within south and central western U.S. protected areas. Most of these plastic particles are synthetic microfibers used for making clothing."

Scientific American explains how microplastics get up into the air and are able to travel vast distances. "Carried by the wind, dust particles from places such as the Sahara Desert can float halfway around the world before settling to the ground. As the plastics discarded by humans break down into tiny pieces in the environment, they, too, drift through the atmosphere."

Image: Gading Ihsan on Unsplash

"We're not supposed to breathe in this material," says Steve Allen, a microplastics researcher at the University of Strathclyde in Scotland…. Plastics in the environment "carry all sorts of pesticides, heavy metals and all the other chemicals that we've made over time," he adds. "They're going to carry them directly into our lungs."

In 2021, Wired reported on a research article from the Proceedings of the National Academy of Sciences on the sources of these airborne microplastics. Some interesting findings:

"84 percent of airborne microplastics in the American West actually comes from the roads outside of major cities. Another 11 percent could be blowing all the way in from the ocean. (The researchers who built the model reckon that microplastic particles stay airborne for nearly a week, and that's more than enough time for them to cross continents and oceans.)

"Microplastics—particles smaller than 5 millimeters—come from a number of sources. Plastic bags and bottles released into the environment break down into smaller and smaller bits. Your washing machine is another major source: When you launder synthetic clothing, tiny microfibers slough off and get flushed to a wastewater treatment plant. That facility filters out some of the microfibers, trapping them in 'sludge,' the treated human waste that's then applied to agricultural fields as fertilizer. That loads the soil with microplastic. A wastewater plant will then flush the remaining microfibers out to sea in the treated water. This has been happening for decades, and because plastics disintegrate but don't ever really disappear, the amount in the ocean has been skyrocketing."

As for how roads become a source of microplastics, the article points out that car tires—which these days, are not pure rubber, but a cocktail of synthetics and chemicals—shed particles as they roll. Which should be obvious to anyone who's ever replaced worn-out tires: Where did all that tread material go? It doesn't just disappear, it just breaks down into smaller particles.

And how do microplastics in the ocean wind up inland? Researchers from New Zealand's University of Auckland—who "calculated that 74 metric tonnes of microplastics are dropping out of the atmosphere onto the city annually, the equivalent of more than 3 million plastic bottles falling from the sky—looked into the source and identified the potential culprit:

Image: frank mckenna on Unsplash

"The production of airborne microplastics from breaking waves could be a key part of the global transport of microplastics," says [Dr. Joel Rindelaub, of the School of Chemical Sciences at Waipapa Taumata Rau, University of Auckland]. "And it could help explain how some microplastics get into the atmosphere and are carried to remote places, like here in New Zealand."

Polyethylene (PE) was the major substance detected, followed by polycarbonate (PC) and polyethylene terephthalate (PET). Polyethylene and PET are packaging materials while PC is used in electrical and electronic applications. All three are also used in the construction industry.

And finally, New Atlas reports that microplastic travel "can be facilitated by winds that collect plastic particles off the surface of the ocean and carry them into the atmosphere, with fragments turning up in Arctic and Antarctic snowfall a sign of the distances they can cover." In other words, there is no place to hide from the microplastics crisis we have created or contributed to.