Comparative study of air quality surveillance networks in Hong Kong

Spatial distribution and temporal variation of 24 h SO2 concentrations are examined to compare the three surveillance networks in Hong Kong, namely Environmental Protection Department, Hong Kong Electric Co. Ltd. and China Light & Power Co. Ltd. Factors affecting the space-time variability of the air quality data were identified and taken into consideration in assessing the monitoring network design. Spatial correlation analysis was computed for the intra-network and inter-network station pairs. Besides synoptic meteorological influence, spatial correlation was found to depend not simply on distance factor but on a combination of controls including local emission characteristics. The findings could be applied to future rationalization of the monitoring networks. Limitation on the Air Pollution Index system in Hong Kong is reviewed, noting the inadequacy of interpolation from the existing EPD network stations.