About 40 per cent less rubbish is washing up on the city's beaches, a massive three-month cleaning campaign suggests.
Glass waste topped the list of coastal rubbish that volunteers collected across 43 locations - among which unmanaged beaches in Tuen Mun and Lantau were found to be the dirtiest.
The drop in the amount of refuse did not mean the coasts had become cleaner or that public awareness had grown stronger, said non-profit environmental group Green Council, organiser of the annual exercise.
Separate clean-up efforts over tonnes of plastic pellets that washed ashore in July could have affected the result of the council's campaign, conducted from mid-September to mid-November.
"Some areas could have been cleaned up after the spill of pellets from six shipping containers that fell into the sea during Typhoon Vicente," the group's chief executive, Linda Ho Wai-ping, said.
Public officers recovered at least 12 tonnes of the 150 tonnes of pellets spilled from a freighter.
In the council's 2012 coastal clean-up campaign, more than 3,000 volunteers gathered 5.6 tonnes of rubbish, down from 9.6 tonnes the previous year, it said.
About 80 per cent of the debris came from beaches without daily management by the Leisure and Cultural Services Department.
"Regular contractors clean up the managed beaches every morning, but it is not the case for those that are not," Ho said.
Lung Kwu Tan and Tai O, both unmanaged beaches, topped the list in terms of the weight and number of pieces of junk found.
Among government-run coastal areas, Rocky Bay Beach in Shek O was the dirtiest.
About 16,000 pieces of broken glass were collected, accounting for 23 per cent of total refuse. Plastic foam boxes, plastic bags and cigarette tips were the next commonly found items.
Volunteers also came across empty liquified petroleum gas containers, broken canoes and pieces of large plastic dollhouses.
Ho said the dominance of glass indicated a lack of recycling measures tackling such waste.
But she had reservations about a proposal to impose a levy on wine or beer bottles as she had no idea how recycled glass would be treated.
Professor Ho Kin-chung, an executive member of the council and dean of the school of science and technology at the Open University, felt that the levy would not be effective in changing people's behaviour.
"Unlike the plastic bag levy, a levy on glass bottles would not result in behavioural changes as there are no other options," he said.
"People can't buy wine or beer in environmentally friendly packaging [such as] recycled bags," he said. It was better to have a system in which bottle producers could retrieve their bottles for reuse, he said.