A slick of carcinogenic benzene, which can cause leukemia and other blood-related cancers, flows down the Songhua River in the northern city of Harbin on Nov. 24, 2005.
A worker carries a sack of coal at a small mine in Shanxi province on Nov. 29, 2006.
A man works in a coking factory in Xian, Shanxi, on Feb. 2, 2007. The factory, which emitted about 300 million cubic meters of exhaust per year, was shut down as part of the local government's campaign to reduce air pollution.
A worker pulls a cart of tiles through aisles in a factory in Foshan, Guangdong province, on Sept. 26, 2008. This town is known for producing ceramics, but the industry has been blamed for acid rainfall in the Pearl River Delta Region.
Workers leave the Wangjialing coal mine, near Xiangning, Shanxi, on March 31.
Tending the ovens at the Xian coking factory in Shanxi on Feb. 2, 2007.
A man shovels coal outside a heating plant in Linfen, Shanxi, on Feb. 15, 2007. Linfen was ranked the world's most polluted city in a June 2007 World Bank study.
Smog blankets a main street in Linfen on Dec. 9, 2009.
A mask-clad woman exercises in Linfen on Dec. 9, 2009.
The skyline of Wuhan city, Hubei province, rises atop of layer of smog on Dec. 3, 2009.
A masked man walks near the polluted Songhua River in Harbin, Heilongjiang, on Nov. 25, 2005.
A group of wild geese fly over the Tai Lake in Wuxi, Jiangsu province, on Feb. 7, 2005. Development in the region, one of the fastest growing in the country, has heavily polluted the once-pristine lake.
