Unmasking the problem of COVID litter

An international team of researchers has confirmed what has been obvious to the eye – around the world, disposable masks have been turning up more in litter during the pandemic.

The researchers, who have published their findings in Nature Sustainability, say that masks, gloves and other personal protective equipment (PPE) form a higher proportion of global litter since the onset of COVID-19.

“Our study looks at the proportion of masks, gloves and wipes to total collected litter,” says co-author Dr Jasper de Bie, a research fellow at Griffith University’s Coastal and Marine Research Centre.

The researchers used data from the citizen science app Litterati to determine whether the PPE was showing up more.

“Litterati is a crowd-based, litter-collection application, one of the largest databases of tagged litter that is openly available,” says de Bie.

“Users with this app upload a geotagged image of a piece of litter they collect, and this is categorised by the app and confirmed by the user.”

The researchers examined data on three types of PPE – masks, gloves and wipes – in 11 different countries, including Australia, from October 2019 to October 2020.

“Using this citizen science data we can observe temporal increase in littered masks, gloves and wipes,” says de Bie.

The researchers found that, by number of items, masks – previously less than 0.01% of global litter – jumped to more than 0.8% of global litter, representing an over 80-fold increase. Gloves and wipes doubled from roughly 0.2% of litter to 0.4% in early to mid-2020, but then dropped back down to pre-pandemic levels.

These proportions differed by country: in Australia and New Zealand, mask litter peaked at less than 0.2% in 2020, whereas in the UK it topped out at 6%. PPE litter also fluctuated in time with restrictions and mandates in different countries.

“There are potential sources of error with this approach, such as poor and inconsistent tagging of items, and spatial bias in effort – eg people may record more items in a city than in the countryside,” says de Bie.

But the researchers are confident that their data holds.

“By collating the data on a national level, this granularity is taken into account, and we could also then relate this to national policies,” says de Bie. “And citizen science does offer access to data that otherwise can be difficult to obtain via smaller-scale studies, especially as this time period occurred under travel and work restrictions.” 

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The researchers point out that in addition to the environmental impacts of this increase in PPE litter (such as choking hazards for animals and microplastic pollution), there are short-term health effects for people, too – these discarded items can still be infectious.

“The COVID virus can survive on a discarded mask for days and thus there is a risk of transmission,” says de Bie.

“The littering is driven by multiple factors, including national policies, such as mandatory mask wearing.

“But in addition, there are factors such as provision of enough bins, bin collections and street cleaning that influence how much litter ends up in the environment. And importantly, there is a public behavioural aspect as well – ie choosing not to litter.”

Australia’s relatively low level of mask litter provides the country with an advantage, according to de Bie.

“We have a good opportunity here to start doing things right and prevent such a surge as the UK has seen,” he says.

“After all, there is a good possibility of continued mask recommendations [and] policies as new variants of COVID emerge.”