US Geological Survey researchers collected rain samples from eight sites, 6 in the Denver-Boulder urban corridor and two adjacent sites in the Colorado Front Range at a higher elevation. The sites are part of a network monitoring changes in the chemical composition of rain.
In 90 percent of the samples, researchers found plastics, mostly fibers and most of which were blue in color.
The plastics were invisible to the naked eye, microplastics, they needed 20 to 40 times magnification to be seen. Plastics were found in samples from a site at an elevation of 10,300 feet in Rocky Mountain National Park.
The findings are detailed in a report published May 14.
Plastic pollution is ubiquitous. Researchers recently discovered plastic fibers in remote mountain regions of France.