Air quality worsens in delta, monitoring network finds
Cheung Chi-fai – SCMP – Updated on May 01, 2008
The Pearl River Delta was hit by poorer air quality last year, with ozone pollution worsening in most cities covered by a cross-border air quality monitoring network, according to a report released yesterday.
The report found the delta suffered from bad to worst air quality 33.81 per cent of the time, up 2.19 per cent from 2006.
The hardest hit city remained Foshan , a major construction materials and ceramics production centre, which had the worst grade of air quality 18 per cent of the time.
Individual pollutants generally recorded a rise in average concentration of between 2 and 7 per cent, with the exception of nitrogen dioxide, which dropped 2 per cent.
The monitoring network, jointly operated by the Environmental Protection Department and the Guangdong Environmental Protection Bureau, covers 16 places including three in Hong Kong, and measures the concentration levels of sulfur dioxide, nitrogen dioxide, respirable suspended particles and ozone.
Data gathered from each monitoring station is used to compile the regional air quality index. Based on the mainland air quality standard, the index is then ranked from Grade I to V, with Grade III to V being bad to worst air quality.
It was the second full-year report since the network started operating in November 2005 to provide a tool for environment officials to gauge the effectiveness of emissions control measures. These measures were implemented after Hong Kong and Guangdong agreed in 2002 to cut emissions of four pollutants by 20 to 55 per cent of 1997 levels, by 2010.
However, the report does not conclude whether real improvement has been made.
While nine of the 16 monitoring stations’ annual nitrogen dioxide readings improved last year, 13 stations’ ozone readings deteriorated. For sulfur dioxide, half of the stations recorded an improvement, but for particulates, 10 stations showed a worsening trend.
The environment department said the lack of rain last year made air pollution dispersion difficult, and higher temperatures and more sunshine made the formation of photo-chemical smog easier. “Short-term air quality is mainly affected by meteorological conditions, and two years’ data is not sufficient to assess the changing trend of air quality.”
It said Hong Kong’s ambient air quality, which was also affected by regional air quality, remained stable last year, with only a slight increase in the annual concentration of nitrogen dioxide, ozone and respirable suspended particles.