China will ramp up the curbing of air pollution in the transportation sector in its next-phase campaign to keep improving air quality, an environment official said on Wednesday.

Liu Bingjiang, director of the Ministry of Ecology and Environment's atmospheric environment division, told a panel of international reporters in Beijing that an upcoming action plan on reducing air pollutants will focus on transportation-induced pollution and there will be a giant leap forward in related work.

"Oxynitrides are now a major airborne hazard," he said at an event organized by the China Public Diplomacy Association.

The pollutants are mainly generated by the consumption of fossil fuels, particularly those consumed in transportation, ranging from passenger cars to heavy trucks to cargo ships, said Liu, who is also a member of the standing committee of the China National Democratic Construction Association, and a political adviser.

He said the action plan, which is still being vetted by central authorities, marks the third phase in China's battle against air pollution.

China issued a five-year action plan in 2013 in response to heavy smog smothering many regions.

The plan was followed up in 2018 with a three-year campaign to protect blue skies and further lower the concentration of PM2.5 — inhalable particles with diameters 2.5 micrometers and smaller.

The efforts combined made China a pioneer in the developing world in addressing air pollution, and one with the greatest progress in air quality, officials said.

China's clean air campaign coincided with the speedy development of the electric car sector, and the rapid increase of electric heavy trucks — heavily used in sectors such as mining and construction and crisscrossing the country — was a major contributor to reducing air pollution, he said.

Authorities have tried to replace gasoline buses with electric ones and limited diesel vehicles in urban areas, he said.

The reforms in the transportation sector are among many measures the government has taken to curb pollution. As part of the campaign, China also shut down many heavily polluting steel plants, promoted gas-for-coal heating projects in rural areas and fostered the renewable energy industry.

Liu noted that China's GDP has expanded by 69 percent since 2013. Meanwhile, the concentration of PM2.5 has dropped 57 percent, a telltale sign that economic growth does not necessarily contradict environmental protection.

Over the past decade, some 60.5 percent of the growth in China's energy consumption came from clean resources, an increase of 41.4 percentage points from the previous decade. China now boasts the world's largest installed capacity for wind, solar and hydropower.