HONG KONG - The use of zero-emission buses on Hong Kong roads is the city government's long-term goal to ease roadside air pollution and improve overall air quality, said Secretary for the Environment KS Wong Monday.

"We launched our Clean Air Plan in March to set the target and also the timeline to meet the objective," he said, adding the goal is to meet the new air quality objective by 2020 and concrete plans are in place for the government to follow.

Hong Kong has subsidized a pilot scheme on the use of zero- emission franchised buses to get solid data and public feedback before considering how to expand the plan.

Wong said the Council for Sustainable Development will launch a public engagement on the quantity-based waste-charging scheme by the end of this month at the earliest.

It is an important step and the city's government looks forward to receiving feedback on the scheme, he said.