BEIJING -- China's air quality improved in 2015, despite the frequent winter smog covering the country's north and east, Minister of Environmental Protection Chen Jining said on Monday.

The average PM2.5 density in 74 major cities dropped 14.1 percent from 2014, and annual emissions of sulfur dioxide and oxynitride were reduced by 5 percent and 9 percent respectively, the minister said at a conference.

Chen noted last year China accomplished the annual target of eliminating vehicles with excessive emissions, supplied cleaner gasoline and diesel nationwide and established air quality forecast and warning systems in key cities.

He said nevertheless it is urgent for the nation to refine pollution treatment methods and improve the emergency response system.

In 2016, China will try to reduce volatile organic chemicals in the petrochemical industry, strengthen management over mobile pollution sources and improve regional coordination in coping with serious pollution such as smog, he said.

The ministry will also continue to implement three action plans targeting air, water and soil pollution in the next five years.