It was not completely blocked in November 2010, but was completely blocked shortly there after as far as I remember (I was in Beijing from 2007 to 2016). China

It was not completely blocked in November 2010, but was completely blocked shortly there after as far as I remember (I was in Beijing from 2007 to 2016). China wasn’t measuring 2.5 ppm at all back then, and was rather touting improvements in 10 ppm because a tree planting effort in the gobi temporarily solved northern china’s dust storm problem. They were basically pretending that 2.5 ppm pollution didn't exist.