One in four Hong Kong people are considering emigrating because of the city's worsening air pollution, according to a survey released Wednesday.

The poll of 1,000 people by the Civic Exchange pressure group found the ratio of residents considering leaving Hong Kong had risen from one in five in 2008 when the study was last conducted.

Nearly 90 per cent of those considering leaving were college degree holders, indicating Hong Kong may face a brain drain because of its poor air quality, the group said.

The key reasons cited for considering emigration were the effect of air pollution on the interviewee's health and the health of their children, researchers said.

Civic Exchange said, "A problem that drives a quarter of the population to consider emigrating is truly staggering. It also appears that less talk and more action is what the public want from government."

There was no immediate response from the government to the survey's findings.

Air pollution has worsened in Hong Kong over the past two decades, caused largely by traffic fumes and pollution from factories in neighbouring mainland China.

Government measures to address the problem have been ineffective so far and officials have been accused of being reluctant to approach the Chinese government to help find a solution.

-- The China Post/Asia News Network