Study: Disposable Covid-19 Masks Release Microplastics and Chemicals That Persist in the Environment

Disposable face masks distributed and discarded during the Covid-19 pandemic can leach microplastic particles and chemical additives even when unused, a laboratory study published in the journal Environmental Pollution found, adding to concerns about long-term environmental contamination and possible human exposure.

Researchers at Coventry University placed new surgical masks and disposable masks with filters in purified water for 24 hours and then analyzed the liquid for particles and chemicals. They detected microplastics — including polypropylene, polyester, nylon and polyvinyl chloride (PVC) — and identified chemical additives such as bisphenol B, an endocrine disruptor. Masks with filters released three to four times more microplastic particles than standard surgical masks, the team reported.

The researchers said the materials and chemicals that leach from these single-use products may accumulate in soil and water where masks are discarded, and could enter food chains and human bodies. Using conservative production estimates from the pandemic period, the study estimated that disposable masks may have released between 128 and 214 kilograms (282 to 472 pounds) of bisphenol B into the environment.

Study co-author Anna Bogush, an associate professor in Coventry's Centre for Agroecology, Water and Resilience, said the work highlights the need to rethink production, use and disposal of single-use masks. "We can't ignore the environmental cost of single-use masks, especially when we know that the microplastics and chemicals they release can negatively affect both people and ecosystems," she said.

The pandemic sharply increased global use of disposable face masks. One analysis cited by the researchers estimated that 1.2 trillion disposable masks were added to the environment worldwide from December 2019 through May 2021. Other estimates put usage at about 129 billion disposable masks per month at the pandemic's peak; regional studies reported Asia used 1.8 billion masks at height compared with 244 million in the United States. The U.S. government distributed roughly 600 million masks between March and September 2020, and some reports said China discarded as many as 500 million pieces of personal protective equipment per day at the peak in parts of the country.

Most disposable masks are made largely of polypropylene and other durable plastics that do not readily biodegrade. Recent research cited by the authors indicates polypropylene may take on the order of centuries to fully decompose, leaving large quantities of material in landfills, on beaches and in oceans where sunlight, wind and mechanical action cause them to fragment into micro- and nanoscale particles.

Microplastics are typically defined as pieces of plastic smaller than 5 millimeters. They have been detected in water, soil, air and food, and in recent years researchers have found plastic particulates in human tissues and fluids, including blood, lung tissue and placental samples. Laboratory and epidemiological studies have associated microplastics and some plastic-associated chemicals with inflammation, changes to the gut microbiome, respiratory problems, circulatory damage and endocrine disruption. Authors of the Coventry study pointed to these findings as reasons to be concerned about widespread environmental release from discarded masks.

The team’s experimental set-up used new, commercially available disposable masks submerged in 150 milliliters of purified water for 24 hours. The controlled conditions were intended to identify what could leach from the products themselves without the complicating effects of wear or environmental exposure. The researchers noted that real-world conditions — exposure to sunlight, abrasion and biological activity — could alter the release profile in either direction, and called for additional field studies.

A 2024 paper in the Journal of Hazardous Materials, cited in the Coventry study, estimated that microplastics from discarded masks account for approximately 3% of marine microplastic emissions. The authors and other experts emphasized that masks were an important tool for infection control during the pandemic and that the study's findings do not negate their protective value in disease outbreaks.

The Coventry team recommended raising public awareness of disposal risks, improving waste management for personal protective equipment, and accelerating development of sustainable alternatives such as reusable masks made from materials that shed fewer fibers or are easier to recycle. They also urged regulatory and manufacturing changes to reduce plastic content or replace problematic additives.

Researchers and public health specialists say future policy responses to respiratory disease outbreaks should consider both infection control and environmental sustainability. The Coventry study urged a balanced approach that retains protective measures while minimizing long-term environmental and public-health consequences associated with massive single-use plastic consumption.

Limitations noted by the authors include the laboratory nature of the experiment, which used purified water and new masks and did not mimic the full range of environmental processes that act on discarded materials. The researchers called for broader monitoring of mask waste in the environment, measurement of real-world leaching under different conditions, and toxicological studies to better quantify human health risks from chronic, low-level exposure to mask-derived microplastics and chemicals.

Until alternatives and improved disposal systems are widely available, public-health officials and waste managers face the dual challenge of mitigating infectious disease risk and preventing long-term pollution from personal protective equipment. The Coventry researchers concluded that reducing single-use plastic waste from masks should be part of planning for future public-health emergencies to protect both human health and ecosystems.