Chinese people wear face masks with "No to Kunming PX," paraxylene, written, chant slogans as they hold protest against a planned refinery project in downtown Kunming in southwest China's Yunnan province Saturday, May 4, 2013. (Associated Press)

Chinese people wear face masks with "No to Kunming PX," paraxylene, written, chant slogans as they hold protest against a planned refinery project in downtown Kunming in southwest China's Yunnan province Saturday, May 4, 2013. (Associated Press)