## 4 Findings and Discussion
### Environmental Impact Produced
#### 4.4.3 Physical and Physico-Chemical Degradation  
Because the composition of PPE is based on plastic [2], the interactions of waste in open environments lead to their physical and physico-chemical degradation [79]. PPE waste will slowly degrade into microplastics (MPs) (5 mm-1 \(\upmu\)m) and nanoplastics (NPs) (<1 \(\upmu\)m) due to physicochemical (e.g., UV radiation, wind, currents) and biochemical (enzymatic activity) processes [3; 14], contributing to the mounting problem of MP and NP pollution [16], in addition to leachable inorganic and organic chemicals' production, which are associated with textiles and plastic additives that have an adverse impact on human health and the environment [80], especially in marine water, resulting in the popularity of the terms marine pollution and environmental impact in our thematic maps (Figures 13b and 14). To combat the negative consequences of MP and NP production, some studies tested the degradation of face masks and wipes into microplastics and nanoplastics under different aging and environmental conditions [20; 21; 22; 23; 24; 80; 81; 82; 83]. They found concentrations varying from \(2.6\times 10^{3}\) to \(6.0\times 10^{9}\) items per face mask [16], including polypropylene (PP) and polyethylene terephthalate (PET) microplastics with different colors. Comparing the types of face mask, the middle melt-blown layer of surgical face masks discharges a greater quantity of MPs and NPs than the outer and inner layers [20; 21]. Hence, the amount of microplastics produced by these face masks is higher than in the case of nonwoven examples. In addition, some studies showed that the use of face masks and wipes comprises new routes for the exposure of humans to plastic particles. Thus, the use of face masks for a prolonged time produces MPs and NPs that can be inhaled. A study reported \(2.6\pm 0.4\)-\(10.6\pm 2.3\) particles of microplastics in adults' nasal mucus secretion [21], and in the case of using wipes for hands, a concentration of 180-200 particles per sheet was reported [23]. Concerning harmful chemical and organic pollutant production, the use of antiviral and antibacterial barriers in face masks and dye compounds, as well as the enhancement of some fashionable properties, such as fragrances and colors, generate nanoparticles classified as emerging contaminants [4], which are expected to contribute to the release of potentially hazardous chemicals [3]. Heavy metals such as Pb, Cd, and Cu are commonly used as chemical additives during plastic manufacture [84], and they were identified by [80] in amounts ranging from 0.01 to 6.79, 0.01 to 1.92, and 0.85 to 4.17 g/L, respectively; Sb with levels ranging from 111 to 393 \(\upmu\)g/L has been mainly associated with colored novelty face masks [80]. In the case of using antibacterial barriers based on Ag and Cu, they produce synthetic or engineered nanoparticles (ENPs). ENPs are particles whose sizes range between 1 and 100 \(\upmu\)m and are made up of many atoms or molecules bonded with each other [15]. All these components have a long-term effect as a potential pollutant in water mass, with extreme danger for aquatic organisms [85; 86]. Finally, evidence of added chemicals in the production of polymer-based face masks is only now emerging [80; 87; 88], indicating that they could also be a source of environmental chemical pollution [16]. Cloth masks manufactured with commercial synthetic textiles are washable and cost-effective and have improved environmental performance [45; 46]. One study reported an 85% reduction in waste due to the use of these reusable masks, with a 3.39-times lower impact on climate change and being 3.7-times less expensive than disposable masks [89]. However, some criticalities, such as the use of fossil-based or impactful materials, as well as an open-loop end-of-life stage, have been identified; therefore, they cannot be considered sustainable [90].