The discovery suggests that microplastics are being carried around the planet in atmospheric winds, and that we’re breathing them in.

Microplastics, those pervasive relics of modern times, have invaded seemingly every part of the planet today, including the most remote reaches of the Arctic. Scientists have been puzzling over how this flood of pollution makes its way to such distant locations far from the urban centers where it’s generated. A new study finds a surprising route for the tiny particles—they’re ferried aloft to fall in the Arctic as snow.

“Substantial” amounts of plastic fragments and fibers are landing atop ice floes in the Fram Strait—an unpopulated expanse of ocean between Greenland and the Norwegian Arctic archipelago of Svalbard—reports the study, published today in Science Advances.

Scientists from Germany’s Alfred Wegener Institute for Polar and Marine Research and the Swiss Institute for Snow and Avalanche Research measured microplastics in snow samples from this remote location during research cruises from 2015-17, and found levels they conclude could only have fallen from the sky. The study raises concerns about how much microplastics contaminate the atmosphere, posing a potential health risk to people and animals that breathe them in.