Photo/Illutration People wear face masks to protect against heavy smog pollution at Tiananmen Square in Beijing on Nov. 14, 2018. (Asahi Shimbun file photo)

SHANGHAI--The 41 cities of China's Yangtze river delta manufacturing hub will aim to cut concentrations of tiny airborne smog particles known as PM2.5 by 2 percent this winter, below last year's target of 3 percent, the environment ministry said, in a new action plan.

China, which is in its sixth year of a war on pollution, has denied claims that it is easing smog-fighting efforts in a bid to rejuvenate its economy, which grew by its slowest rate in nearly 30 years in the third quarter.

The eastern coastal region, spanning the commercial hub of Shanghai and the neighboring provinces of Jiangsu and Zhejiang, is one of China's key smog control zones, which cut average PM2.5 levels by 8 percent last winter.

The major steel producing region will also impose output curbs on foundries that exceeded utilization rates last year, and ensure more of them meet ultra-low emissions standards this winter.

Particles that are considered especially hazardous, PM2.5 in the Yangtze delta stood at an average of 39 micrograms per cubic meter in the first three quarters of the year, down 2.5 percent but still higher than the state standard of 35.

Since 2017, major industrial regions have adopted special plans to disperse smog build-ups in winter, when emissions from China's largely coal-fired heating systems soar.

The Fenwei plain region in northern China, another key smog control zone covering big coal-producing provinces such as Shanxi, Henan and Shaanxi, will also aim to cut average PM2.5 levels by 3 percent, the environment ministry added.

Last year, the region missed its 4 percent target.

The 28 cities of the Beijing-Tianjin-Hebei region, also in the north, were told to cut PM2.5 by an average of 4 percent over the winter, but the change is not expected to be sufficient to offset the 6.5 percent increase last year.

This year, China expects particularly unfavorable weather in winter, likely to bring more smog throughout its north.

"PM2.5 reduction targets seem lower than previous years, but it won't be easy for us to actually reach the targets," environment ministry spokesman Liu Youbin told a recent news briefing.

"We will never relax our efforts to push forward the anti-pollution campaign or ease the pressure on local authorities, who will still face punishments if they fail to hit targets this year."