Public electricity generation is one of the major sources of RSP emission. It contributed to 32% of total emission in 2006. The import of nuclear electricity from Daya Bay of the Mainland in 1994 and the use of natural gas for power generation since 1995 had resulted in a downward emission trend. The increase in 2003 and 2004 was due to the increased power generation from coal-fired units. After setting emission caps to the power companies in 2005, the emissions in 2006 have decreased by 20%.