Microplastics released from face masks used during the COVID-19 pandemic: A review of the characterization techniques

The excessive use and incorrect disposal of personal protective equipment (PPE) during the COVID-19 pandemic have aggravated the problem of plastic and microplastic (MPs) pollution in the environment. In particular, disposable face masks (DFMs) are subject to increasing concern due to their effects on marine biota and the release of MPs, as well as other pollutants such as heavy metals and phthalates esters. The present review discusses different existing characterization techniques, such as Fourier-transformed infrared spectroscopy (FTIR), Atomic Force Microscopy (AFM), and Scanning Electron Microscope (SEM) coupled with an energy-dispersive Xray analyzer (EDX), and X-ray diffraction (XRD), to evaluate the topographical, morphological, structural, and compositional characteristics as well as the surface of littered DFM and MPs released. The combined use of characterization techniques has been crucial to understanding how and to which extent the physical, chemical, and mechanical properties of DFMs contribute to MPs and plastic pollution in the world.