Conservation groups say they're increasingly concerned about surgical masks being carelessly discarded into the local environment – with dozens of masks found washed up on a beach, and photos shared online of masks also littering hiking trails.
Oceans Asia has been conducting surveys into marine and micro-plastic pollution on the Soko Islands, south of Lantau.
They had chosen those islands because they're so remote, get few visitors and aren't regularly cleaned by the government. That helps them to understand the composition and build up of rubbish over time.
Gary Stokes said their most recent visit – their first since the coronavirus outbreak – showed just how quickly pollution reaches our shores.
"The population was really introduced heavily into using surgical masks about six weeks ago. And it has taken six weeks and now we are seeing the effect," he said.
Stokes said they found about 70 masks on the 100 metre stretch of beach. He said no matter whether the masks came from Hong Kong or elsewhere in the Pearl River Delta, they're marine debris and shouldn't be there.
He also said the masks could be mistaken for food by marine life – and the area has turtles, dolphins and finless porpoises. If the masks are eaten, they could block up the animals' digestive tracts and kill them.
Ken So from the Conservancy Association also warned about disposing rubbish and face masks on the city's hiking trails.
"If you leave any rubbish in the countryside, that may affect the habitat of wildlife," he said.
"So remember when you are visiting the countryside, no matter if it is country park or not, please prepare well so that you bring back all your rubbish," said So.
Photos have been shared online suggesting the city's hiking spots are littered with rubbish, including discarded surgical masks.
But So said that while more people may have been taking to hiking trails as an escape from being cooped up at home over the past few weeks, he hasn't noticed a huge increase in the amount of rubbish there.