The findings equate to 1.4m residents thinking about moving away, including 500,000 who are "seriously considering or already planning to move," according to the survey by the think tank Civic Exchange.

Those most seriously thinking about fleeing the city include top earners and highly educated workers, raising questions over the southern Chinese city's ability to attract and retain top talent, the report's authors found.

"People from all sectors of society know that air pollution is making them sick," said Michael DeGolyer, a political science professor at Hong Kong Baptist University.

"Many are concerned to the point they are considering leaving Hong Kong, including local professionals."

DeGolyer added that the survey of more than 1,000 residents debunked the myth that concerns about air pollution were confined to the city's foreign residents, as only three percent of the respondents were expats.

The research also found that concern about pollution had risen rapidly since 2001, and that managers and administrators were some of the most worried.

"And Singapore wants them," DeGolyer told reporters, referring to the long-standing rivalry between the two Asian cities to attract top talent.

Air pollution across some parts of Hong Kong last year reached its highest level since records began, official figures released last week showed.

A spokesman for the Environmental Protection Department said tough measures had helped reduce the levels of several pollutants in recent years and it was working closely with neighbouring Guangdong province, whose factories are the source of much of the city's pollution.

"The government shares the aspiration of the public for clean air and has been implementing strong measures to control our emissions at source, particularly from road transport and power generation," the spokesman said, in a statement.

A Civic Exchange report last year said that at least 10,000 deaths were caused every year in Hong Kong, Macau and southern China by the region's worsening air pollution.

Hong Kong Chief Executive Donald Tsang has called improving air quality a "matter of life and death" for the city, but has still to introduce new air quality standards, 20 years after the current set was brought in.