Despite high pollution readings, air is cleaner, government claims
Daniel Sin – SCMP – Jan 03, 2009
The Environmental Protection Department has insisted Hong Kong’s air quality has improved over the past decade, despite its air pollution index showing big rises in the number of hours pollution hit dangerous levels.
A departmental spokeswoman said concentrations of individual pollutants were a better means than the API to assess the long-term air quality trend and had been decreasing over the past 10 years. These air pollutants include respirable suspended particles (RSP), nitrogen oxides (NOX), sulfur dioxide and ozone.
The department was responding to a South China Morning Post (SEHK: 0583, announcements, news) report that showed the number of hours in which street-level pollution exceeded dangerous levels at three crowded areas had increased over the past year, in some cases to record levels.
The department’s data shows the average level of roadside RSP last year was 72 micrograms per cubic metre, down 13.3 per cent from 2004. In the same period, the concentration of nitrogen oxides fell 2 per cent, while that of sulfur dioxide was constant.
Statistics from general stations suggested that the concentrations of individual pollutants they recorded had dropped by an average of 1.7 per cent to 5.3 per cent each year between 2004 and last year.
The department attributed the improvement to the success of control measures taken by Guangdong province in recent years.
To improve regional air quality, the Hong Kong and Guangdong governments agreed in 2002 to reduce the emissions of four major air pollutants by 20 to 55 per cent from their 1997 levels by 2010. To achieve this, they drew up a regional air quality management plan focusing on key sources of emissions, the spokeswoman said.
But Simon Ng Ka-wing of the Hong Kong University of Science and Technology questions this.
“The levels of RSPs and NOX concentration recorded last year still exceeded the respective one-year air quality objectives, and have in fact breached our lenient air quality objective every year over the last 10 years,” he said. “They are much higher than the safety margins recommended by the World Health Organisation, which is 20 micrograms per cubic metre for RSP and 40 for NOX.”
Last year, the average concentration of NOX at roadside stations was 99 micrograms per cubic metre.
“Roadside air quality is still posing a serious health threat to Hongkongers,” said Dr Ng.
Mike Kilburn, of think-tank Civic Exchange, said the government should adopt the WHO’s air quality guidelines.