HONG KONG (Reuters) - Roadside air pollution in Hong Kong hit record highs in the first six months of the year, hurting public health and economic competitiveness compared with Asian rivals, activists and lawmakers said Tuesday.

The city’s air quality hit “unhealthy” levels about 10 percent of the time between January and June, the highest level in five years, said environmental group Friends of the Earth.

The government advises people with heart or respiratory problems to avoid lingering in traffic-heavy places when the air pollution index goes into “unhealthy” territory.

“Think of the health cost and also the disincentives to tourists and to people investing and setting up companies in Hong Kong,” said legislator Audrey Eu who joined green activists in unfurling a big black banner over a roadside monitoring station at the heart of Hong Kong’s Central financial district.

Health experts estimate poor air has cost the city HK$1.18 billion (US$151 million) in healthcare bills and lost productivity, along with 3.8 million visits to the doctor, this year.

“The bad air and pollution is actually giving Hong Kong a bad name and deterring people from coming,” added Eu, who was among a coalition of lawmakers urging the government to do much more to resolve the problem including accelerating the phasing out of diesel buses and imposing stiffer fines.

Hong Kong’s air pollution soared off the charts to unprecedented highs in March when sandstorms from northern China cloaked the city in dust.

A survey by Mercer Consulting ranking the quality of life of 221 cities, found air pollution weighed heavily on Hong Kong, a business gateway to China, knocking its ranking to 71, far below Singapore at 28.

“Hong Kong’s always been rated lower than other neighboring cities ... it’s due mainly to our air quality problems,” said Edwin Lau, director of Friends of the Earth.

“The government seems to have done a lot of things, but I would say they’ve only been tinkering on the edges,” said Lau, referring to a recent law to ban idling engines.

He noted, however, that imported pollution from China’s vast industrial hinterland of the Pearl River Delta, across the border from Hong Kong, had shown mild improvement over the past year given a push to phase out older, more polluting industries there and other emission-reduction measures.

Hong Kong’s Environmental Protection Department had no immediate response when contacted by Reuters, but earlier noted that while roadside pollution had peaked, overall atmospheric pollution levels actually fell in the first six months.