Overall concentrations of most pollutants were generally higher last winter and fell as summer approached, the first regional air quality monitoring network report has found.

The report, covering the regional air pollution situation for December to June, was released today by the Environmental Protection Department (website) and Guangdong Environmental Protection Bureau (website). It records the concentration of major pollutants, like sulphur dioxide, nitrogen dioxide, ozone and respirable suspended particulates.

It found the overall concentration of pollutants fairly high in March, possibly attributable to frequent stagnant air streams during the month.

The department said monthly variations in the concentration of pollutants can change from year to year, adding long-term monitoring is required before a general pattern can be concluded.

The monitoring results for the year will be available in April 2007.

The network comprises 16 monitoring stations, 13 in Guangzhou (Shenzhen, Zhuhai, Foshan, Zhongshan, Huizhou, Dongguan, Jiangmen, Zhaoqing, Shunde, Huiyang, Panyu and Conghua) and three in Hong Kong (Tsuen Wan, Tung Chung and Tap Mun). The network was commissioned last November.