What the Rain Carried
When Hurricane Helene dropped 20 to 30 inches of rain on the southern Blue Ridge, it also delivered something no one could see. A three-site study, with samplers running straight through the storm, measured how much.
Most of what we remember about Helene is what we could see: brown water where a creek used to be, a road that was there on Wednesday and gone by Friday. This story is about the part that fell quietly alongside it. Microplastics, fragments too small to notice, travel through the air and settle out with rain and wind, even into headwater country far from any city.
A team from Virginia Tech, Western Carolina University, Highlands Biological Station, and the University of North Carolina at Chapel Hill had been measuring that fallout at three sites in western North Carolina before the storm arrived. Their samplers separated what settled on dry days from what came down with rain. When Helene reached the southern Appalachians on September 25, 2024, the samplers were still collecting.
That timing is what makes the study unusual. According to the team, it is the first in the United States to measure microplastic deposition before, during, and after a hurricane. The results appeared this year in Integrated Environmental Assessment and Management, and its authors include members of the Station community: Associate Director Jason Love, Highlands Field Site Director Dr. Rada Petric, and James Campbell, an HBS volunteer and retired physicist and engineer who helped with the project's rainfall instrumentation. You can read more about Jim in his volunteer spotlight.
Photo courtesy of Nathaniel Barrett (permission TK).
A share of the whole year, in a few days
Helene's rain brought a large slice of a full year's microplastic deposition, and the size of that slice differed from one site to the next. Choose a site to see its number.
Highlands Biological Station
Here on campus, the storm accounted for 18.8 percent of the year's microplastic deposition, nearly one-fifth of it, and the largest share of the three sites.
Coweeta Hydrologic Laboratory
At the research site in Macon County, Helene made up 4.6 percent of the annual total.
Iron Duff
At the Haywood County site, the storm's share was 4.2 percent of the year.
Bars show Helene's share of each site's annual deposition. With three sites, the researchers are careful not to claim these figures describe every place the storm reached.
From three sites to a whole region
Across the three sites, deposition during the storm ran anywhere from three to twenty-two times higher than it had before it. To see the bigger picture, the Virginia Tech team worked with civil engineer Hosein Foroutan to estimate how much microplastic the storm deposited across the region it crossed, which includes most of the southeastern United States.
Their estimate is about 3,850 trillion particles deposited by Helene. That is a modeled number, offered to give a sense of scale rather than a count anyone could make from the ground.
A second, quieter pulse
The rain was not the end of it. After the storm, the samplers also caught more microplastics on dry days than they had before the storm.
Graduate student Nathaniel Barrett, who works in Gray's Aquatic Toxicology and Ecology Lab, offers one idea for why. It is a hypothesis the team plans to test, and they did not measure plastic on leaves directly, so treat the steps below as a question and not a result.
“The microplastic footprint Helene left behind was pretty substantial.”
Austin Gray, Virginia Tech biologist
What the study can and can't say
The work shows that extreme weather can quickly change where plastic pollution lands. It does not show what those particles did once they arrived. Gray points out that microplastics settle across land and water, most of all after storms, which changes what it means to call a place “impacted,” since the particles may have started out far away.
The team lists the questions that come next.
- How far did the footprint reach? Three sites cannot describe every place Helene touched.
- What does it mean for living things? The risks to human health and to biodiversity remain open, and the team notes that the Southeast has a great deal of vulnerable biodiversity.
- How do we follow the particles? Better ways of tracking microplastics as they move through the environment would sharpen every other answer.
Highlands sits in the southern Blue Ridge, a global biodiversity hotspot, and this work builds on earlier monitoring of its rivers, forest soils, and rain. Jason Love traces the earlier chapters of that story in another dispatch.
Related · NFF·004The Air We Breathe, the Water We Share
Associate Director Jason Love traces microplastics through Western North Carolina, from rivers and forest soils to the rain itself. Read the dispatch →
Read the paper
Influence of Hurricane Helene on microplastic deposition in the mountainous southeastern United States.
Austin Gray, Jason Love, Nathaniel Barrett, James Campbell, Jerry Miller, Radmila Petric, Robert Youker, Xinyue Huang, and Hosein Foroutan. Integrated Environmental Assessment and Management, 2026.
This dispatch is based on the study and on the Virginia Tech News release “Hurricane Helene deposited nearly one-fifth of annual microplastics at one North Carolina site” by Kelly Izlar (September 24, 2026). Read the original release. Researchers are affiliated with Virginia Tech; Western Carolina University, including Highlands Biological Station; and the University of North Carolina at Chapel Hill. Notes from the Field is published by Highlands Biological Station, a center of Western Carolina University.
TK: confirm attribution wording and photo permission with Dr. Gray's group before publishing.