Microplastic runoff from road traffic can pollute waterways.
When rubber tires and brake linings wear down from friction, microplastic particles break off and are swept along with rain runoff into inland waterways and coastal waters. A 2020 Nature study found that road-traffic microplastics are carried into the ocean not just by water, but by wind. About a third of microplastic particles are deposited in the ocean from the air.
Microplastics are defined as tiny plastic pieces less than 5 mm long, about the size of a sesame seed.
In recent decades, India has used a polymer glue made from shredded plastic waste (like shopping bags and foam packaging) as a strengthening agent to create thousands of miles of plastic roads. These roads make use of trash that would otherwise enter a landfill, but they're also likely to shed microplastics as they deteriorate.