SIERRA NEVADA, Calif./Nev. – A study published at the end of October found that snowstorms can capture and deposit a significant amount of microplastics onto the ground, including in remote locations in the Sierra Nevada.

“We are at a point where microplastics are in our atmosphere, not just the ocean, not just rivers. It comes down with the snowfall, making its way to places humans typically don’t go,” Aleksandra Karapetrova said, the study’s lead researcher and a UC Riverside environmental toxicologist.

While past studies have already established that microplastics occur in Western U.S. snow, this study examined how much is being deposited on the ground during individual storms.

The study surveyed seven sample sites during active storms in the Sierra Nevada between January and July 2024, taking care to ensure the locations were remote.

“One site was accessed by chairlift. I had to ski to the rest of the remote sites. That’s how isolated they are,” Karapetrova said. “But no matter how far out the site, I always found microplastics there.”

Scientists were surprised at the amount at the remote locations. During the height of storms, snow deposited between 270 and 3,200 plastic particles per square meter, per day.

The study explained that in a process called snow scavenging, snowflakes can capture airborne plastics and carry them to the ground. It explains how microplastics get deposited far from populous centers or places where plastics are used or produced.

Karapetrova also found that the most common microplastics deposited are those used in clothing and packaging, including polyethylene, polypropylene, and polyester/PET.

Microplastics can enter the air when products shed or wear down into fragments small enough for the wind to carry. With clothing in particular, studies have found that plastic fibers can enter the atmosphere through dryer vents or daily wear.

The findings raise important implications since the Sierra Nevada snowpack supplies 30% of California’s freshwater.