Pollutant concentrations were within National Ambient Air Quality Class 2 Standards for 72% of the first half of the year.

The regional air quality index found coastal areas less polluted than the central and northern areas of the Pearl River Delta, due to the better dispersion of pollutants.

The Environmental Protection Department and Guangdong Environmental Protection Bureau today announced the results of the report on the monitoring results of the Pearl River Delta Regional Air Quality Monitoring Network for January to June.

The network measures concentrations of sulphur dioxide, nitrogen dioxide, ozone and respirable suspended particulates. The overall concentrations of most pollutants were generally higher in winter, and lower as summer approached.

Besides heavier rainfall and a higher mixing layer, the cleaner maritime airstream brought by the southern monsoon saw reduced pollution over the summer.

Intermittent high levels of pollutants exceeding Class 2 - applicable to general residential areas - was recorded in all monitoring locations, mainly due to meteorological conditions unfavourable to pollutant dispersion.

The report can be viewed here. Monitoring results for all of 2008 will be available in April.