The behavior of microplastics and nanoplastics release from UV-aged masks in the water

In this study, three types of disposable masks were exposed to ultraviolet (UV) irradiation to determine the effect of UV irradiation on the release of microplastics (MPs) and nanoplastic (NPs) from the masks. A kinetic model was used to investigate the mechanisms of M/NP release from the masks under UV irradiation. Results showed that UV irradiation exacerbated the damage to the structure of the mask over time. As the irradiation time increased, the middle layer of the mask was damaged first (15 d) and subsequently all layers of the mask were damaged (30 d). There was no significant difference in the quantity of M/NPs released from the treatment groups at different irradiance during a 5-d irradiation period. When the UV time reached 15 and 30 d, the highest quantity of M/NPs was released at 8.5 W/m² followed by 4.9 W/m², 15.4 W/m², and 17.1 W/m². Exponential equations fitted the release curve of M/NPs. The release quantity of M/NPs increases exponentially with increasing UV irradiation time, and the longer the irradiation time, the faster the rate of increase. Estimated release of 1.78 × 10¹⁷-3.66 × 10¹⁹ particles/piece of MPs and 8.23 × 10¹⁹-2.18 × 10²² particles/piece of NPs into the water when the masks are exposed to the real environment for 1-3 years.