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Report urges wider monitoring of damaging superfine particles

Joyce Ng, SCMP

The superfine particles in Hong Kong’s air that critically affect people’s health should be monitored at all 14 air-monitoring stations, consultant firm Ove Arup says, while setting the loosest target for the government to meet.

None of the annual average readings of the five stations that record the concentration of the superfine particles known as PM2.5 – in Tsuen Wan, Tung Chung, Yuen Long, Tap Mun and Central – met the lowest World Health Organisation standard between 2004 and 2007, according to data released by the Environmental Protection Department yesterday.

Last year stations reported 24-hour average concentrations of superfine particles exceeding the WHO standard 39 times. The particles can penetrate deep into human lungs and cause respiratory and heart diseases. US and local studies have shown the particles can cause lung cancer and affect lung growth in children.

Ove Arup, noting the impact of the particles on public heath, recommended that the government monitor PM2.5 at all 14 monitoring stations and publicise the readings – based on the least stringent of the three interim WHO standards.

At present, the department only releases readings on the larger PM10 particles to the public, although it also measures PM2.5 at five stations. Ove Arup blamed regional rather than local sources for PM2.5 pollution, pointing to the case of Tap Mun island in Sai Kung, which is free of any local emissions but still recorded PM2.5 pollution readings exceeding WHO guidelines by 13 times last year.

“Based on air-quality monitoring data and the fact that Hong Kong’s particulate-matter emissions account for only about 1 to 2 per cent of the entire emissions in the Pearl River Delta region, it is apparent that the concentration in Hong Kong is subject to very strong regional influence,” Ove Arup’s report said.

Ameliorating measures could still be taken locally, it said, proposing the early retirement of heavily polluting diesel buses and trucks, because road vehicles contributed 25 per cent of the city’s PM2.5 emissions.

If phase one measures were implemented, about 4,200 unnecessary hospital admissions would be avoided, it estimated.

Wong Tze-wai, head of the community medicine department at Chinese University and a member of the panel that advised the government on its air-quality-objectives review, said the standards for reducing fine particles were too lax but it was inaccurate only to blame regional sources for high PM2.5 concentrations.

“These fine particles are easily dispersed. They can disperse from traffic in Tai Po to Tap Mun. So the pollutants in Tap Mun do not necessarily come from the mainland,” Professor Wong said.

Marine transport was also a source of PM2.5, he said, but the government was not willing to ban vessels entering Hong Kong from using cheap and dirty bunker fuel for fear of hurting the logistics industry.

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