Disposable tri-layer masks and microfiber pollution - An experimental analysis on dry and wet state emission

The use of masks as a personal protective material is the new normal in the post-pandemic. The higher use of masks triggers immediate disposal of synthetic textile fibers leading to environmental pollution. This research is aimed to analyse the level of mask-related pollution and its impact on microfiber release. Microfiber emission characteristics of the tri-layer nonwoven mask (Polypropylene-based disposable mask) are analysed in the dry and wet stages. The individual layers of the mask and the entire mask are evaluated by subjecting them to static immersion and mechanical agitation against freshwater and seawater in the wet stage. The results of the study showed a higher microfiber shedding at dry state (14,031.97-177,601.58 fibers/mask) than the wet state (2557.65-22,525.89 fibers/mask). The increased fuzz formation in the dry state than the wet state is noted as the main reason. In the case of wet state, when the freshwater and seawater are compared, both in a static and agitated state, seawater degraded the mask highly (3358.03-27,348.9 fibers/mask) than the freshwater (1757.26-17,702.86 fibers/mask). Higher salinity and density of the seawater were noted as influencing parameters over the freshwater. When the results of naturally weathered masks are compared with the new mask, weathered masks released significantly (p < 0.05) higher amount of fibers at the evaluation stages. Similar to the new masks, the weathered masks also showed a higher amount of shedding in the dry state and presence of seawater. When the individual layers of the disposable masks were evaluated, at dry and wet states, all the layers showed a similar shedding (no significant difference between individual layers) in the case of a new mask. Whereas, after weathering, a significant amount of higher shedding (p < 0.05) is noted in the middle layer of the mask followed by the outer and inner layer. The difference in fiber composition is noted as the main reason for the strength difference of the nonwoven structure. Statistical analysis confirmed the significant impact of the natural weathering process and seawater on the microfiber shedding.