Beijing closed a large coal-fired power plant on Wednesday, replacing it with a gas-fired one to cut pollution.

The Gaojing Thermal Power Plant, a subsidiary of the state-owned China Datang Corporation, shut down six coal-fired power generation units, according to the municipal development and reform commission.

There are four major coal-fired power plants in Beijing. The 50-year-old Gaojing plant is the first to be closed. The other three are expected to be closed by the end of 2016 when power will be wholly generated by clean energy.

Beijing is building four gas-fired power plants to reach the 2016 target of cutting 9.2 million tons of coal consumption, and cutting emissions of 10,000 tons of sulfur dioxide, 19,000 tons of nitric oxide and 3,000 tons of dust annually.

Beijing's average PM2.5 index of 91.6 micrograms per cubic meter in first half of 2014 represents an 11.2 percent year-on-year decrease.

The airborne particles smaller than 2.5 microns in diameter are blamed for Beijing's smog. The figure is still far above the national standard of 35 micrograms per cubic meter, said the report by Beijing Municipal Environmental Protection Bureau.

In September 2013, a five-year plan was introduced in the city to slash coal consumption, promote clean energy use and reduce production capacities of heavy polluters.