China will strive to eliminate heavy air pollution in 70 percent of its major cities by 2025, according to an action plan unveiled on Thursday.

Jointly issued by 15 central government bodies, including the Ministry of Ecology and Environment and the National Development and Reform Commission, the plan also vows to reduce the annual proportion of days with heavy air pollution in the country to below 1 percent.

The plan was drafted against the backdrop of a "grim" air pollution control situation despite "remarkable" improvement in air quality, according to a media release from the ministry.

Last year, the average density of PM2.5 particulate matter reached 30 micrograms per cubic meter, down by 34.8 percent from 2015, the release said. Also last year, 87.5 percent of the days in China had fairly good air quality, 6.3 percentage points higher than in 2015.

However, days with heavy air pollution still happen frequently in autumn and winter in the Beijing-Tianjin-Hebei province cluster.

"Heavy air pollution events still happen in over half the cities across the country," it said.

It also cited ozone as an increasingly bigger contributor to air pollution, especially during the summer. The average density of ozone across the country has increased by 6.4 percent so far this year, it said.

The action plan outlines a series of moves to realize the targets.

The country will endeavor to further optimize its industrial structure and promote low-carbon transition in the energy sector, the plan said.

It said intensified efforts will also be made to reduce coal consumption occurring at a small scale in a non-concentrated manner, which generally results in more air pollutants compared with concentrated consumption.

Furthermore, additional measures will be rolled out to beef up the management of diesel-powered trucks, which is major contributor to oxynitride emissions, according to the plan. For example, an online platform will be established to monitor such vehicles.