(Yicai Global) June 10 -- China's air quality has improved significantly in the decade ended in 2017 due to governmental efforts, according to the vice minister of the Ministry of Ecology and Environment.

Sulfur dioxide content decreased by 72 percent over those 10 years, and oxynitride levels fell by 34 percent, Zhao Yingmin said at a press conference today, citing results of a national census which surveyed different sources of emissions, including millions of firms.

Chinese companies and cities have become much less polluting, said Zhao. Industrial firms have paid more attention to wastewater treatment, desulfurization, and dust removal, he added. The number of urban sewage treatment plants increased by over five times in 10 years, and that of waste disposal facilities almost doubled.

The census shows that some of the most-polluted areas include the Beijing-Tianjin-Hebei region, Yangtze River Delta, and the Fenwei Plain in the middle reaches of the Yellow River.

The industrial and economic powerhouses of northern Hebei, southern Guangdong, as well as eastern Zhejiang, Jiangsu, and Shandong provinces, made up nearly 53 percent of the country's emission sources.

Editor: Emmi Laine