The research team was led by Dr. Henry He Yuhe, Assistant Professor in CityU's School of Energy and Environment (SEE) and a member of the State Key Laboratory of Marine Pollution (SKLMP). The findings were published in the academic journal Environmental Science and Technology Letters, titled "Release of Microplastics from Discarded Surgical Masks and Their Adverse Impacts on the Marine Copepod Tigriopus japonicus."

Plastic material widely used in surgical masks

The research team cited an estimate by a US environmental protection organization that global demand for surgical masks reached 129 billion per month by 2020. And some research estimated that owing to the lack of proper collection and management policies, 1.56 billion masks were inappropriately released into the ocean in 2020.

"Polypropylene (PP) is the main material widely used in surgical masks. It is a kind of commodity plastic that can break down under the effects of heat, wind, ultraviolet radiation, and ocean currents, eventually forming microplastics," said Dr. He. Microplastics are usually smaller than five millimeters and can take hundreds of years to degrade in the ocean.

A walk with his dog on a beach triggered Dr. He's interest conducting the research. "I saw one mask wedged between rocks on the shore and another floating on the water surface. Since all the masks are made of plastics and may be releasing microplastics, improperly discarded masks will affect the marine environment. I believe this problem will continue for many years in the post-pandemic era," said Dr. He.