1 Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC, H3G 1M8, Canada.
2 Department Research and Development, Meltech Innovation Canada Inc., Medicom Group, Pointe-Claire, QC, H9P 2Z2, Canada.
3 Environmental Systems Engineering, 3737 Wascana Parkway, Regina, Saskatchewan, Canada, S4S 0A2.
4 Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC, H3G 1M8, Canada. Electronic address: chunjiang.an@concordia.ca.

The disposal of fossil fuel-based plastics poses a huge environmental challenge, leading to increased interest in biodegradable alternatives such as polylactic acid (PLA). This study focuses on the environmental impact and degradation of PLA face mask components under various conditions (UV (Ultraviolet) radiation, DI water, landfill leachate of various ages, seawater, and enzyme). Under UV exposure, notable changes in physicochemical properties were observed in the PLA masks, including increased oxidation over time. Degradation rates varied across environments, with old landfill leachate and enzyme degradation having a notable impact, especially on meltblown layers. Furthermore, it was found that seawater conditions hampered the degradation of PLA masks, likely due to the inhibitory effect of high salt concentrations. The pathways of chemical group changes during degradation were elucidated using 2D-COS (Two-Dimensional Correlation Spectroscopy) maps. The investigation into the release of microparticles and oligomers further revealed the degradation mechanism. Moreover, PLA masks were found to release fewer microparticles when degraded in studied environments when compared to traditional polypropylene masks. Furthermore, correlation analysis highlighted the influence of factors such as carbonyl index and contact angle on degradation rates, underscoring the complex interplay between environmental conditions and PLA degradation. This comprehensive investigation advances the understanding of PLA degradation pathways, which are crucial for mitigating plastic pollution and promoting the development of sustainable products.