SHIJIAZHUANG, March 13 (Xinhua) -- China's leading steelmaking city, Tangshan, has announced new restrictions on steel production in order to improve air quality, according to local authorities.

The city will extend production restrictions on steel mills once the current curbs expire on March 15, Tangshan Development and Reform Commission said.

New restrictions will take effect from March 16 and end on November 14.

Tangshan has cut nearly 44.7 million tonnes of steel production capacity since 2013 in an effort to control air pollution.

In 2017, the average density of PM2.5 in the city was 66 micrograms per cubic meter, down 42.6 percent from 2013.