China's Environmental Protection Ministry has completed an analysis of the primary pollutants in nine major cities in the country, the China Youth Daily reports.
The study covered Beijing, Shanghai, Guangzhou, Shenzhen, Shijiazhuang, Hangzhou, Ningbo, and Nanjing.
According to the Ministry, exhaust fumes from vehicles was the major pollutant in Beijing, Hangzhou, Guangzhou and Shenzhen.
Shijiazhuang and Nanjing were mainly affected by burning coal.
The primary pollutants in Tianjin, Shanghai and Ningbo were dust and emissions from motor vehicles and factories.
