The full results of the Pearl River Delta Regional Air Quality Monitoring Network for 2007, which measured the concentrations of four major pollutants, has now been released.

The pollutants measured were sulphur dioxide, nitrogen dioxide, ozone, and respirable suspended particulates, and the report said air quality in the region was better in the coastal areas than in the central and northern region of the Pearl River Delta in 2007, which could be attributed to the relatively more favorable conditions for dispersion of pollutants in the former. Hong Kong's Environmental Protection Department and the Environmental Protection Bureau of Guangdong Province issued the results.

The overall concentrations of most pollutants were generally higher in the winter months, and apart from heavier rainfall and higher mixing layer, the relatively clean maritime air stream prevailed in the PRD region under the influence of southern monsoon also accounts for a lower level of pollution in summer time. Two-thirds of the Regional Air Quality Index as recorded by the Network in 2007 were in Grade I or II, meaning the pollutant concentrations are within Class 2 National Ambient Air Quality Standards.

The environmental monitoring authorities of the two sides will continue to monitor the changes in the regional air quality and regularly announce the latest monitoring results. The monitoring results for the first half of 2008 are expected to be available in October 2008.