Air pollution in Beijing reached hazardous levels again this week, but the push toward openness about what's in the air continues.
Until recently, officials refused to release information about small particular pollution — potentially the most dangerous, unseen contaminants in the capital's air.
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Beijing has begun reporting more fully about the contents of its smog, in large part because of a massive citizen movement tracking the air through monitors established by the US Embassy in Beijing and published on Twitter and Sina Weibo.
As the air broke the hazardous barriers again this week, officials told the China Daily newspaper that the air was indeed dangerous.
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"The Chinese Center for Disease Control and Prevention suggests people stay at home to protect themselves from respiratory and heart problems triggered by heavy smog," the paper reported this week.
"The intensity of indoor pollutants is 30 to 60 percent lower than those outdoors during a hazy day," Xu Dongqun, a Beijing environmental official told the paper. "I suggest people with respiratory problems put off traveling if the smog lingers."