In 2017, Janice Brahney was examining dust that had blown across the wilderness of the Western United States to determine its nutrient composition. She slid her samples under a microscope, expecting to see the usual quartz and feldspar grains, pollen and random bug parts.
Instead, what leaped from the lens were candy-colored shards and spherules — blue, pink and red plastics mixed with the dust like foul confetti.
“I was really taken aback when I saw this,” said Brahney, an assistant professor of biogeochemistry at Utah State University. “I had no idea that our pollution had extended to that level.”
Sensing a potential discovery, Brahney, along with fellow researchers, started monitoring dust deposits in nearly a dozen protected areas in the West — places we tend to think of as relatively pristine, like Joshua Tree National Park, Rocky Mountain National Park and the Grand Canyon
At each location, they found microplastics blown in on the breeze. In a study released Friday in the journal Science, they reveal just how much plastic is landing on protected areas in the West: more than 1,000 tons each year, equal to 123 million to 300 million pulverized plastic water bottles.
Not many hikers huffing up a mountain trail would realize they might be breathing in components of what used to be somebody’s snazzy nylon pants. Minuscule plastic particles — microplastics made from artificial clothing fibers, broken-down consumer products, beads used in medical and industry applications and other sources — are practically undetectable to the naked eye.
But they’re ubiquitous now, thanks to a world that generates hundreds of millions of tons of plastic every year.
Study adds to mounting evidence of a growing human plastic footprint
The study found microplastic particle sizes that ranged between four and 188 microns. The smallest were as tiny as one-tenth the width of a human hair, and the largest were twice the size of fine beach sand. Some of the smaller particles can, if ingested, become lodged in human lungs.
We’ve known for decades that plastics litter the oceans, accumulating in floating garbage patches, piling up like landfills in deep-sea trenches and being eaten by the tiniest organisms in the marine food chain.
But it hasn’t been until recently that scientists realized it was flying above our heads, similar to how dust particles are picked up by the wind. One of the first studies on this phenomenon came out in 2015 — though the precise mechanisms of uptake and deposition and, more importantly, their consequences are still poorly understood.