At a workshop in Seoul, two environmental activists melt down old plastic bottle caps that thousands of volunteers known as "sparrows" have collected in a bid to fight a tide of plastic the novel coronavirus has helped unleash.

Green activists Kim Yona and Lee Dong-I use the bottle caps to make a tube-squeezing device — something they hope consumers will find useful and be able to keep, rather than toss out after just one use.

"Plastic is a recyclable resource," said Kim, 26. "But it’s way too cheap, easy to make and easily thrown away, which makes people think it's disposable."