The bad news - Hong Kong is one of the world's most polluted cities. The not-so-new news - most of the pollutants are wafting across the border from the mainland.
That is the preliminary verdict of a group of Hong Kong Polytechnic University scientists at the official launch Thursday of the university's 10-year air pollution monitoring partnership program in conjunction with the United States' National Aeronautics and Space Administration.

"What surprised us is that when we compared pollution in Hong Kong on a normal day, it was always higher than other cities like Taipei, Paris and Washington," said Janet Nichol, university associate professor of land surveying and geo-informatics.

But she was quick to add that the SAR's pollution was "not always higher than Beijing's."

Nichol and her team of experts, who have been monitoring the level of aerosols, or pollutant particulates, in the air in Hong Kong and the mainland since last October, are convinced the territory's pollution woes are the product of factories located across the border, not from cars or other local sources.

"Green groups have been saying that 80 percent of our pollution comes from the mainland, and our observations point strongly to that," Nichol said.

An eight-day experiment conducted over the Lunar New Year holidays showed a drastic drop in pollution levels, she said - evidence that the pollution had been coming from mainland factories which were closed during that period.

Under its agreement with NASA, the university receives daily satellite images of China, which indicate pollution levels through varying shades of gray. Images usually show that much of China, south of Beijing and extending about three kilometers into the sea, is blanketed under a thick sheet of murky gray, Nichol said.

Nichol and her team also use a HK$250,000 device called a sun- photometer, placed on the roof of the university library, to measure the amount of aerosols in the atmosphere during daylight hours. The results are then sent to NASA's Aerosol Robotic Network, which includes about 150 other cities and sites around the world.

But Nichol admitted she did not know whether the results will be used by the Environmental Protection Department, which she said is using an "outdated" and "not accurate" approach. She said the government's air pollution index is not sensitive enough, but could be improved if combined with data from satellite images such as NASA's.

Green group Friends of the Earth, which has long called for a review of the index, said Hong Kong's current system lags behind other countries in that it measures only coarse particulates, not the finer particulates that are more easily inhaled into the lungs.

"It's good news that academics are very concerned about air pollution and are setting up scientific hardware," said group assistant director Edwin Lau. "I hope the government is open-minded and understands that this information is scientific information.

"It's neutral and not biased toward any side."

Source: http://www.thestandard.com.hk/news_detail.asp?pp_cat=11&art_id=14966&sid=7205094&con_type=1