The proliferation of face coverings to protect against COVID-19 has had a devastating, lasting effect on the environment, with a 9,000% increase in mask litter over 14 months in 11 countries, finds an observational study led by UK researchers yesterday in Nature Sustainability.

Discarded gloves and used disinfectant wipes have also added to the refuse, the increase of which was likely driven by national COVID-19 policy responses—particularly face mask mandates—and World Health Organization (WHO) recommendations, the researchers said.

Litter poses a big threat to the environment, potentially clogging drains and sewage systems; polluting rivers, lakes, streams, and oceans; entangling and poisoning wildlife; and leaching contaminants such as microplastics into the lower food chain.

Mask litter increased 84-fold

The researchers, from the University of Portsmouth and the University of Southampton in England and Griffith University in Australia, quantified the emergence of single-use personal protective equipment (PPE) and pandemic-related litter—much of it made with plastic—using the Litterati citizen-reported litter-collection app from September 2019 through October 2020. More than 2 million pieces of trash were collected during the study.

Participating countries were Australia, Belgium, Canada, France, Germany, the Netherlands, New Zealand, Spain, Sweden, the United Kingdom, and the United States.

In the 4 months leading up to the WHO announcement of a global health emergency, the volume of masks, gloves, and wipes collected remained stable, with the proportion of masks at less than 0.01% of all trash and gloves and wipes at about 0.2%.

After the WHO announcement, quantities of all types of PPE litter increased, with gloves spiking 2.4% but then falling to about 0.4% above prepandemic levels. Volumes of wipes gradually rose from March to August, at 0.6% over previous levels, declining to about 0.4%.

Mask litter increased 9,000% from March to October, peaking at 0.84% of all litter. "Importantly, these proportions were observed alongside an increase in the total number of litter items recorded in Litterati, indicating that this was not an artefact of sampling," the authors noted.

In March 2020, the WHO estimated an increase in monthly demand for healthcare settings alone of 89 million masks and 76 million gloves^,the authors said. By October 2020, discarded masks had increased 84-fold over the previous year.

Over the first 6 months of the pandemic, the WHO advised that the general public should not wear masks in order to conserve limited supplies for healthcare workers but then revised its guidance on Jun 5, 2020, to recommend their use in settings in which physical distancing was impossible and in countries with ongoing community transmission.