I lived in Beijing for fifteen years and the pollution is one of the primary reasons I returned to the United States. The image above is what the city can look like both on a ‘clean air day’ and a polluted one. The image below is what I remember in downtown Beijing, on most days.  In fact, it seemed there were fewer and fewer ‘clean air days’.

NPR has done this investigation, which describes inside air quality being “…five times higher than the level considered safe by the U.S. Environmental Protection Agency.”  Listen to the story here as well.  NPR Beijing Pollution 12-7-11