Why is the air quality index at the U.S. Consulate different from the Environmental Protection Agency’s index?

First of all, the US Embassy has only one monitoring point, while the Environmental Protection Agency has many atmospheric monitoring points, and the pollution index released is also averaged (may be weighted). Therefore, from the perspective of monitoring, the government’s refutation of the U.S. Embassy’s data also makes sense. Just an overreaction.

In addition, there is the more controversial PM2.5. The method used by the US Embassy to monitor particulate matter is the beta-ray attenuation method, which measures the amount of particulate matter based on the blocking of rays by particulate matter in the air. Our country's national standard is the mass method, which means collecting and weighing the mass of particulate matter for measurement. Therefore, different methods will naturally bring about differences in data.