Health authorities say the most widespread anti-Covid weapon—surgical masks—must be thrown away after a single use, but environmental concerns are pushing some scientists to question this recommendation
As the coronavirus continues to spread, face masks have in many places become mandatory on public transport, in shops and at work.
But the cost has become an issue, as has the fact so many disposable plastic masks wind up in waterways and the oceans.
One alternative is reusable cloth masks, but many people prefer single-use surgical masks because they are lighter and individually cheaper.
"Medical masks are for single use only," the World Health Organisation has said. "Discard the mask immediately, preferably into a closed bin."