While face mask pollution has been a common sight throughout the pandemic, Canadian researchers are now learning that sun exposure could be making microplastic pollution even worse.
Single-use masks — also called “disposable” — are typically made from polypropylene. During testing, researchers exposed masks to simulated shoreline conditions and observed how the masks broke down. They exposed the masks to UV light for up to 48 hours, while keeping a control group of masks wrapped in aluminum foil.
The testing showed that exposure to UV essentially tripled the amount of microplastic particles released, compared to masks without UV exposure. The melt-blown cloth in the middle layer of masks was found to be particularly sensitive to UV irradiation, the study states.
“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 states.
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Some 1.5 million microplastic particles are being released into shoreline environments after just 36 hours of a discarded single-use face mask being exposed to the sun, the research team found.
The study was published in the Journal of Hazardous Materials in September and involved researchers from Concordia University, the University of Regina, Fisheries and Oceans Canada, and Memorial University.
An estimated 129 billion face masks are used globally each month, according to a June 2020 study led by Portuguese researchers.
The Canadian study reveals 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,” the authors wrote.
Disposable face masks typically consist of three layers: an inner layer (soft fibres), middle layer (melt-blown filter), and an outer layer, which are non-woven fibres, usually water-resistant and coloured.