Kinetic characteristics of microplastic release from commonly used masks in aquatic environment

Abstract Masks-related microplastic pollution poses a new threat to the environment and human health that has gained increasing concern. However, the longer-term kinetics of microplastic release from mask in aquatic environments have not been studied, which hampers its risk assessment. Four types of masks, Mask 1 (normal mask), Mask 2 (fashion mask), Mask 3 (N95 mask), and Mask 4 (disposable surgical mask), were exposed to simulated natural water environments to determine the time-dependent microplastic release characteristics at 3, 6, 9, and 12 months, respectively. In addition, the structure changes of employed masks were examined by scanning electron microscopy. Moreover, Fourier transforms infrared spectroscopy (FT-IR) was applied to analyze the chemical composition of released microplastic fibers. Our results showed that the stimulated natural water environment could degrade four masks and produce microplastic fibers and fragments in a time-dependent manner. The size of released particles/fibers is dominant below 20 µm across four mask types. The physical structure of all four masks was damaged to varying degrees. Collectively, we characterized the long-term kinetics of microplastic release from commonly used masks. Our findings suggest that urgent action must be taken to properly manage disposable masks and ultimately limit the health threats associated with discarded masks.