By some estimates, people have discarded 4,900 million tonnes of plastic have into the environment. Once in nature, that plastic starts to degrade, fragmenting into microplastics about the size of a sesame seed, which are inadvertently ingested by humans and animals through eating them in seafood and drinking them in water. Some reports suggest that we all consume five grams a week–about the weight of a bottle cap.
But, we may be taking more plastics into our systems through our respiratory systems. There’s been less investigation of nanoplastics: particles smaller than microplastics, so small that they can move huge distances in the air and be more easily inhaled into the bloodstream. A new study looks at the travel of those lighter particles, finding them abundant in the atmosphere, and carried, via aerosol transmission, even to remote areas. As far as the scientists know, it’s “the most accurate record of air pollution by nanoplastics ever made.”
These nanoplastics—smaller than 200 nanometers in size—are microplastics that have broken down even more over time, as well as tiny particles that our everyday plastics, like clothing, shed into the atmosphere. At that microscopic size, the plastics become airborne. “They are so small that they can be transported like normal aerosols in the air,” says Dominik Brunner, a researcher at Empa, the Swiss Federal Laboratories for Materials Science and Technology, and an expert on atmospheric transport modeling.
The team, from Utrecht University in the Netherlands, who Brunner assisted with the transport modeling, designed a technique for measuring the concentration of nanoplastic particles in a sample of material—in this case, a clump of snow—which is often a mixture of many different particles, from Sahara sand to shedded brake pad material.
They chose a remote location in the high Austrian Alps and then used their technique to find and analyze the nanoplastics they found there. They knew that plastics are present in urban areas, but how far could they travel? Their base was atop the Hoher Sonnblick mountain in Hohe Tauern National Park in Austria, home to a meteorology and geodynamics observatory, 3,106 meters in altitude. Every day for a month and a half, they took a chunk of a top level of snow and analyzed its mass spectrometry, essentially thermally releasing the collected material, then using a machine to measure the sample’s molecules. Once identified, they matched them with known types of plastics, such as polyethylenes and polypropylenes.
Then, using a widely employed particle dispersion technique, and European weather service models, they traced back where those particles originated, following individual air parcels back in time. They found that the plastic particles mainly came from densely populated urban areas, but 30% came from more than 100 miles away, including major cities like London, Paris, Amsterdam, Frankfurt, Stuttgart, and Munich.
The urban sources did not surprise the scientists, but the distances traveled did. “Because they are so small, they are transported by wind over large distances,” Brunner says. Some traversed even farther distances: 10% came from more than 1,000 miles away, including some from the Atlantic Ocean, suggesting that some of the lighter plastics accumulated at the surface of ocean can return into the atmosphere.
This also means that you are breathing in nanoplastics from the air around you. The smaller the particles, the larger the risk of inhalation. The scientists judge that those smaller than one micrometer (0.000001 meters) in diameter can “penetrate deep into the lungs,” versus those larger, more than 10 micrometers, which “are likely filtered out by the upper respiratory system.”
While nanoplastics are probably not more toxic to the body than microplastics, it’s the size of the molecules that pose the concern, and the fact that they’re present in large quantities even in remote areas: The amount of nanoplastics deposited per square meter of surface snow each week high in the Alps was 2.8 times more than depositions of microplastics found in the French Pyrenees in a study from 2019.