The weather has been quite wet recently in Beijing, and it’s hard to tell if that fog is just humidity or smog… The average API over the first 15 days of July is only 73, well below the average value of 100, so it seems our daily portion of rain, and a bit of wind, clears the air quite well. We had the same monthly average in February which was an exceptionally clear month (see below).
However, as i have reported on many occasions before, the correctness of official data from the Beijing Environmental Protection Bureau, and the Ministry of Environmental Protection, may be questioned (in addition to the dubious changes in monitoring stations). BBC measured PM10 values last week of more than double the officially reported values as reported in this article, but in their enthusiasm they compared the reported API directly with their measurements of PM10 (microgram per cubic meter). API and PM10 are not the same as i explain here. So in fact the reported values are up to 50% higher than shown in their graph, and much closer to their own measurements. By coincidence this makes it look more spectacular of course… For example the API value of 8 July is 98, which corresponds to a PM10 of slightly less than 150, but in the BBC graph it is shown as 98 on the PM10 scale.
In addition, they did not mention how/where these measurements where made, which makes it rather a scientifically unsound claim if you ask me. Although i do not doubt that the actual levels could be much higher than officially reported, i wonder if a sample measurement of a presumably handheld device on one spot can give a value truly representing the city situation. I am sure more journalists will be making their own measurements, which can give correct values for the air at a particular place at a particular time, but should not be compared to the officially reported API.