Researchers estimate more than 1,000 tons of microplastics, equal to more than 123 million plastic water bottles, are deposited from the air into national parks and wilderness areas each year. Utah State University assistant professor Janice Brahney and her team used high-resolution atmospheric deposition data to identify microplastics and other particulates collected over 14 months in 11 national parks and wilderness areas. In a report in Science, they identified the plastic and polymers composition to track its sources and movement, and found that most of the plastics deposited in both wet and dry samples were microfibers sourced from both clothing and industrial materials. Approximately 30 percent of the particles were brightly colored microbeads likely derived from industrial paints and coatings.

Brahney says, “We confirmed through 32 different particle scans that roughly 4 percent of the atmospheric particles analyzed from these remote locations were synthetic polymers.” The same high resilience and longevity that makes plastics useful lead to progressive fragmentation instead of degradation in the environment. Clear and white particles were not included because they did not meet the criteria for visual counting, so estimates of plastic deposition were conservative.