Plastic rain is theatmospheric deposition ofmicroplastics—particles and fibers less than 5 mm in size—onto the Earth's surface throughprecipitation (wet deposition) or gravitational settling (dry deposition).[1][2] While microplastics were initially categorized asmarine pollutants, subsequent research has identified their presence in theatmosphere, where they can be transported over long distances by wind currents before settling in terrestrial and aquatic environments.[3][4]
The study of atmospheric microplastics emerged following the standardization of the term "microplastics" in 2004 to describe plastic fragments in marine environments.[5] The potential for atmospheric fallout was documented in 2015, when researchers identified microplastic fibers settling in the urban environment ofParis, France.[3]
In 2019, research extended beyond urban centers to remote locations. A study conducted in theFrench Pyrenees demonstrated that atmospheric transport mechanisms could carry microplastic particles to high-altitude, uninhabited regions approximately 100 kilometers from the nearest major accumulation sources.[4]
A 2020 study published inScience further characterized the phenomenon by distinguishing between wet deposition, where particles are scavenged by rain or snow, and dry deposition, where particles settle during non-precipitation events. The study estimated that more than 1,000 metric tons of microplastics are deposited annually in protected areas of the westernUnited States, suggesting that the atmosphere facilitates the global transport of plastic particulates.[1]
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