Chinese authorities have issued a circular on further promoting the nationwide battle to prevent and control pollution, vowing to bring down the country's average density of PM2.5 particulate matter by 10 percent from last year by 2025 in major cities as the country forges ahead with its ambitious climate targets.

According to the Ministry of Ecology and Environment, the average density of PM2.5 — particulate matter smaller than 2.5 microns that is harmful to health — across the country is 33 micrograms per cubic meter of air.

Jointly released on Nov 7 by the Communist Party of China Central Committee and the State Council, the country's Cabinet, the circular said China also aims to see the proportion of days with good air quality in cities at or above the prefectural level reach 87.5 percent, up by half a percentage point from last year's level.

In a media release issued after the publication of the circular, the ministry vowed a series of measures to bring the targets into reality.

It will strive to accelerate the adjustment of industrial structures in key regions and sectors for air pollution control.

"Consistent efforts will be made to promote the campaign on cleaning up diesel engines," it said.

Diesel engines are a major contributor to air pollution in China.

Despite accounting for only about 4 percent of internal combustion engines in Beijing, diesel trucks contribute 90 percent of the particulate matter from such engines, according to research conducted by the city's ecological environment bureau.

The shift of cargo transportation from roads to railways and ships will be accelerated, the release said.

It said ozone pollution control in summer will also be one of the ministry's focuses as it intensifies air pollution management. It will synergize efforts to reduce emissions of nitrogen oxides and volatile organic compounds.

Summer is usually the peak time for ozone pollution as sunlight and high temperatures can trigger chemical reactions between primary air pollutants such as nitrogen oxides and VOCs to form ozone.

The gas can damage the lungs and result in shortness of breath if people breathe in even a relatively low amount of it.

At a recent news conference, Wu Xianfeng, deputy director of the ministry's air quality management department, said China faced a "grim" air pollution control situation that was "not optimistic at all", partly because of ozone pollution.

"In some regions, some of which are key for air pollution control, the ozone density in summer is still on a slow increase," he said. "When we have yet to fundamentally address PM2.5 pollution and heavy air pollution events, the problem of ozone pollution is emerging."

China aims to see its carbon dioxide emissions peak before 2030 and realize carbon neutrality before 2060. The country's low-carbon transition is another main concern of the recent circular.

As the total discharge of major pollutants continues to decline, the country will by 2025 reduce carbon dioxide emissions per unit of GDP by 18 percent from the level in 2020, it said.

By 2035, a green way of life and production will have been formed and carbon emissions will stabilize and decline after reaching a peak, it said.