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People wearing face masks walk near the Forbidden City during heavy pollution in Beijing on February 28, 2013. Beijing residents were urged to stay indoors Thursday as pollution levels soared before a sandstorm brought further misery to China's capital. AFP PHOTO / Ed Jones (Photo credit should read Ed Jones/AFP/Getty Images)

People wearing face masks walk near the Forbidden City during heavy pollution in Beijing on February 28, 2013. Beijing residents were urged to stay indoors Thursday as pollution levels soared before a sandstorm brought further misery to China's capital. AFP PHOTO / Ed Jones        (Photo credit should read Ed Jones/AFP/Getty Images)