Vehicles make their way along a highway as fog covers most of Beijing on March. Thick fog and air pollution covered the city dropping to "hazardous" level in early March this year. AFP/Getty Images
Visitors look out at the skyline clouded by pollution in Shanghai on May 15, 2012.AFP/Getty Images
Girls wear face masks to protect against pollution in the streets of Beijing in December 2011.AFP/Getty Images
Vehicles making their way along a road on a smoggy day in Beijing on January 18, 2011. AFP/Getty Images
Chimneys of factories are seen in Guangzhou in November 16, 2010. AFP/Getty Images
A man walks through heavy pollution on a street in Beijing on November 2011.AFP/Getty Images