The atmospheric settling of commercially sold microplastics

The atmosphere plays a major role in the dispersion of microplastics in the environment. The atmospheric transport of large microplastics is strongly influenced by their settling behavior, which depends on their physical properties, including size and shape. However, experimental data on the settling behavior of commercially available microplastics with complex, nonspherical shapes in air are rare. Here we present experiments on the gravitational settling velocity of commercially available glitters (nominal diameters between 0.1 and 3 mm) and fibers (lengths between 1.2 and 5 mm). We observed that glitters and fibers settle up to 74% and 78% slower compared to volume-equivalent spheres, respectively. The atmospheric transport of fibers has been studied previously; however, there are no studies on the atmospheric transport potential of glitters. Therefore, we used an atmospheric transport model constrained by our experimental results to assess the transport potential of glitters. Our results reveal that glitters exhibit transport distances 12 %–261% greater than volume-equivalent spheres, highlighting their elevated atmospheric transport potential. As a result, the environmental impact of glitter particles, especially following their use in entertainment events, warrants attention and mitigation.