The routes of the Hong Kong marathon may be overhauled in a bid to reduce runners' exposure to air pollution.
The idea was unveiled after a green group reported that pollution levels at certain black spots of the Standard Chartered Hong Kong Marathon on Sunday were up to five times higher than World Health Organisation guidelines.
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Marathon organisers said they might be able to use open space around the Kai Tak sports complex after it was completed in 2020, meaning runners would not have to cross from Kowloon to Hong Kong Island via a tunnel.
"The entire route can be revised once the complex is completed, as it will provide a lot of new open space and roads," said Kwan Kee, chairman of the organiser, the Amateur Athletic Association.
He said the 28-hectare sports complex could see organisers keeping the marathon in Kowloon and the New Territories.
Levels of respirable suspended particles were two to three times more than WHO standards at certain black spots long Sunday's routes, the Clean Air Network found.
For the 42-kilometre marathon, average concentrations of PM2.5 - airborne particles measuring 2.5 microns or less which are the most hazardous to health - hit 63 micrograms per cubic metre, roughly 2.5 times the WHO's recommended 25mcg. In the Western Harbour Tunnel, PM2.5 concentrations were up to five times higher than recommended.
Kwan said there were many challenges to laying out suitable marathon routes in Hong Kong but the committee would explore the feasibility of any options.
"We've been discussing perhaps using one of the sports complex venues as an ending point. This way, runners can avoid running through cross-harbour tunnels, where pollution is high."
Clean Air Network chief executive Kwong Sum-yin welcomed the Kai Tak idea as an "interesting change", but said more needed to be done in the meantime.
"They could follow marathons in Europe or the US and block off all lanes of roads for marathon runners to use," she said. "Routes should also be revised to let runners run in more open air."
Kwan said a possible short-term change was being discussed with the government - to have runners take Hennessy Road instead of the adjacent Lockhart Road before reaching Victoria Park. He said because Hennessy Road was wider, it did not trap pollution as much as Lockhart Road.
Baptist University physical education professor Dr Lobo Louie Hung-tak said air pollution, unless extremely severe, would not have a significant impact on runners' health. But bad air quality would affect the event's international reputation.