BEIJING - Emissions of four major pollutants in China have dropped year-on-year during the first half of this year, China's environmental watchdog said on Wednesday.

The COD index, a measure of water pollution, decreased by 2.26 percent, while the volume of sulfur dioxide emissions, a main indicator for measuring air pollution, totaled 10.37 million tons, a drop of 1.87 percent year-on-year, the Ministry of Environmental Protection said in a statement.

Ammonia nitrogen emissions totaled 1.23 million tons in the first six months of this year, a decrease of 2.67 percent, and nitrogen oxide emissions were cut by 5.82 percent from the same period last year, the statement said.

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