The findings indicate that particles are being carried through the air to some of the most remote locations on earth.
Researchers believe the microplastics were blown through the air across large distances.
Precipitation then caused the particles to fall to the ground in isolated areas.
Their findings raise the prospect of plastic pollution in the air, as well as across land and sea.
Microplastics are pieces which are smaller than 5mm. They emerge when man-made materials disintegrate.
The scientists found the highest concentration of plastic particles in the Bavarian Alps.
Researchers found 154,000 particles per litre in a snow sample gathered near a rural road in Bavaria.
“While we did expect to find microplastics, the enormous concentrations surprised us,” said Melanie Bergmann, a marine ecologist who co-led the research.
The team’s research indicates that fragments may become airborne in a way similar to dust and pollen.
Martin Wagner, a biologist at the Norwegian University of Science and Technology who wasn’t involved with the study, said the extremely high concentrations could be partly attributed to the methods the researchers used.
The team’s methods allowed them to identify particles as small as 0.011 mm — less than the width of a human hair.
“This is significant because most studies so far looked at much larger microplastics,” he said.
“Based on that, I would conclude that we very much underestimate the actual microplastics level in the environment.”
Ms Bergmann said many of the plastic samples found in the Arctic during previous studies had probably been carried there through the atmosphere.
“Once we’ve determined that large quantities of microplastic can also be transported by the air, it naturally raises the question as to whether and how much plastic we’re inhaling,” she said.
The samples detected in the new study included varnish, rubber found in tyres and materials that could have originated in textiles or packaging.
Ms Bergmann and her team believe airborne distribution should be considered in standard air pollution monitoring schemes.
“We really need to know what effects microplastics have on humans,” the marine ecologist said.
“Especially if inhaled with the air that we breathe.”
The study was published in the journal Science Advances.
Additional reporting by agencies
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