Disposable masks release microplastics to the aqueous environment with exacerbation by natural weathering

Highlights: • Disposable masks are widely observed on shorelines during the pandemic. • Physicochemical features of disposable masks changed dramatically under UV weathering. • The transformation of chain structure and decreased mechanical strength were observed. • Masks can be broken into small pieces, releasing a large quantity of microplastics. • Around 1.5 million particles can be released from a disposable mask after weathering. The COVID-19 pandemic has driven explosive growth in the use of masks has resulted in many issues related to the disposal and management of waste masks. As improperly disposed masks enter the ocean, the risk to the marine ecological system is further aggravated, especially in the shoreline environment. The objective of this study is to explore the changing characteristics and environmental behaviors of disposable masks when exposed to the shoreline environment. The transformation of chain structure and chemical composition of masks as well as the decreased mechanical strength of masks after UV weathering were observed. The melt-blown cloth in the middle layer of masks was found to be particularly sensitive to UV irradiation. A single weathered mask can release more than 1.5 million microplastics to the aqueous environment. The physical abrasion caused by sand further exacerbated the release of microplastic particles from masks, with more than 16 million particles released from just one weathered mask in the presence of sand. The study results indicate that shorelines are not only the main receptor of discarded masks from oceans and lands, but also play host to further transformation of masks to plastic particles.