BEIJING -- China has achieved in advance its pollution reduction targets for two major air and water indices, Zhou Shengxian, minister of environmental protection, said Wednesday.

The index for sulfur dioxide, an air pollutant, had dropped 13.14 percent by 2009 compared to 2005 levels thanks to the closing of small thermal power plants and steel plants, Zhou said at meeting in Beijing.

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The Chemical Oxygen Demand (COD) index, a measure of water pollution, had decreased 9.66 percent by 2009 from 2005 levels, and, in the first half of this year, it dropped another 2.39 percent, he said.

The Chinese government set out to reduce COD and sulfur dioxide levels by 10 percent of 2005 levels by 2010.

"This means we have realized the goals in advance," Zhou said.

Zhou pledged more efforts to reduce pollution in major rivers and lakes as well as in the air over the next five years.

Environmental protection authorities will add two items to its major pollutant monitoring list in next five years, he added.

The two new items will be Ammoniacal nitrogen, a major water pollutant, and Nitrogen oxides, a major air pollutant.

Currently, authorities only monitor COD and sulfur dioxide.

The authorities will also strengthen supervision of drinking water sources and step up spot checks around factories releasing pollutants like heavy metals.