Author: Antonio Da Roza
80% - 95% of the total tonnage of air pollution in the Pearl River Delta comes from mainland China sources.  In tonnes, Hong Kong only accounts for 1% - 15% of total emissions in the Pearl River Delta. 
This total emission method of calculating air pollution emissions is useful on a regional scale to depict the volumes in terms of tonnage from different sources. Based on 1997 data, analysis results showed that the Pearl River Delta Economic Zone (PRDEZ) contributed 88% of VOC, 95% of Respirable Suspended Particulates (RSP or PM10), 80% of Nitrogen Oxides (NOx), and 87% of Sulphur Dioxide (SO2) to HKSAR in the base year of 1997.