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Pollution mostly local, study finds

Cheung Chi-fai, SCMP

Sulphur dioxide pollution in Hong Kong is mostly generated in the city, particularly in the container port and by shipping, a leading atmospheric scientist has found.

Dr Alexis Lau Kai-hon, an associate professor at the University of Science and Technology’s Institute for the Environment, said the findings of a study suggested that pollutant criteria proposed in the government’s air quality review had to be tightened further or public health would continue to be at great risk.

Lau recently compared sulphur dioxide concentration data for winters and summers between 2007 and this year. He found that sulphur dioxide concentrations were higher in summer, when southerly winds from the ocean prevailed, than in winter, when northerlies blew from the mainland.

“It suggests the pollution source is local rather than regional,” he said.

Lau found some of the highest sulphur dioxide concentrations in and around the Kwai Chung container port area, indicating that cargo ships and port operations were a big source of pollution. He said they had huge health effects at ground level.

While power generation remained the single largest source of sulphur emissions in Hong Kong, accounting for nearly 90 per cent, Lau said that the shipping sector’s effects on health could be five times greater than that of power plants because of the port’s close proximity to more than three million residents. The medical community has long warned that exposure to high concentrations of sulphur emissions can impair respiratory functions and aggravate existing heart and lung diseases.

Lau said the emissions data studied also showed a remarkable difference in concentrations before and after the global economicdownturn, which began towards the end of last year.

Sulphur dioxide concentrations fell by an average of 25 per cent after the downturn began, when there was an 11 per cent drop in the number of cargo ships, Lau said. The first eight months this year saw 19,790 vessels calling at the port, compared with 22,340 in the same period last year.

Lau said the findings highlighted the urgent need to address air pollution from marine sources, as most ocean-going vessels were still using fuel oil with up to a 2.5 per cent sulphur content. That was 2,500 times higher than the sulphur content in diesel fuel used by road transport.

Lau said pollution by ships was a huge problem, and criteria proposed by the Environment Bureau under the air quality objectives review seemed far too loose to protect people’s health.

The proposed sulphur emissions objective, an average daily concentration of 125 micrograms per cubic metre of air – the lowest interim target allowed by the World Health Organisation – had already been met, Lau said. A more stringent standard of 50 micrograms per cubic metre of air should be used, he said. That would bolster moves to clean up pollution.

“Without a further tightening of the sulphur dioxide standard, there is little basis for further control of the pollutant in the marine sector even though we know the sulphur-laden fumes from marine sources are posing a significant health threat to the population,” Lau said.
Nineteen measures, ranging from using cleaner fuel for power generation to phasing out polluting vehicles, have been proposed by the bureau. None specifically tackle emissions from ocean-going ships.

The only ship-related measure was a proposal, without a clear time frame, to require local vessels, including ferries, to use low-sulphur diesel fuel.

According to a report last year by the Civic Exchange think tank, the pollution related to port activities and ocean-going vessels could also be addressed by designating Hong Kong and its neighbouring regions as sulphur-emission control areas.

A similar zone is in place in the Baltic Sea and North Sea, where ships are only allowed to burn fuel with a sulphur content of 1.5 per cent or less. But any proposal for such a designation for Hong Kong would have to be raised by Beijing at the International Maritime Organisation, which sets global fuel-use standards for ships.

The organisation has also endorsed a plan to limit sulphur content in cargo-ship fuel to just 0.5 per cent sulphur content by 2020, although the port of Los Angeles has already implemented that.

On Wednesday, Secretary for the Environment Edward Yau Tang-wah told lawmakers that the government would raise the low-emission shipping zone issue with the mainland in discussions on post-2010 emission-reduction matters.

An existing agreement on emission-reduction issues will expire by the end of next year.

Arthur Bowring, managing director of the Hong Kong Shipowners’ Association, said ship-fuel issues needed to be tackled from both global and local angles.

He said there should be local laws in Hong Kong and Guangdong to control ship fuel, and both places should endorse such laws simultaneously so that all ships entering the region had to comply.

Bowring said that it would neither be practical nor conducive to fair competition to unilaterally impose fuel restrictions in either Hong Kong or Shenzhen but not both together. But he said he was optimistic that a cross-border agreement would be ready in a few years.
“It will need strong government and political will to put it in place. With the right incentives, right regulations and funding, it can be done.”

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