Hong Kong’s general air quality improved last year compared to 2014, but high ozone levels, which mainly stem from vehicle and factory emissions in China’s Pearl River Delta region, need to be brought down further, according to the Environmental Protection Department (EPD).
According to data unveiled Tuesday by the government agency, concentrations of all major pollutants dropped in 2015.
Air Pollution Indexes indicated by the general and roadside stations showed 3,385 hours of “high” pollution and 1,926 hours of “very high” or “serious” pollution last year, marking declines of 13 percent and 7 percent respectively from 2014, Sky Post reported.
That said, the hours of high pollution in three districts, namely Central and Western, Eastern, Tai Po and Causeway Bay, were up 12, 31 and 7 percent, respectively, from a year earlier.
Mok Wai-chuen, assistant director of environmental protection, said the increased pollution in the districts was mainly due to more easterly wind passing through the city last year.
What’s worth noting is that the ozone level in 2015 was still 32 percent higher than in 1999, although it dropped slightly by 2 percent from 2014.
Stressing that the ozone problem can only be tackled through collaboration with mainland authorities, Mok said the two sides will prepare for a mid-term review on the emission reduction results for 2015 so as to finalize the emission cut targets for 2020.
Ozone is known to cause various types of respiratory diseases and one could die of exposure to high concentration of it.
Wang Tao, a professor at the Department of Civil and Environmental Engineering at the Hong Kong Polytechnic University, said ozone in Beijing and Shanghai can drift to Hong Kong due to wind.
Autumn appears to be most serious season for the toxic pollutant when northeasterly wind tends to dominate, he said.
While ozone in the city mainly comes from the mainland, Hong Kong itself should also bear some responsibility because many factories in Guangdong province are operated by Hongkongers, he said.
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