What are the pm of mild, moderate and severe smog?

In the first half of 20 12, it was stipulated that air quality index (AQI) should replace the original air pollution index (API). AQI*** is divided into six grades, from excellent grade I, good grade II, light pollution grade III and moderate pollution grade IV to heavy pollution grade V and heavy pollution grade VI. When the daily average concentration of PM2.5 reaches 150 μ g/m3, the AQI reaches 200; When the daily average concentration of PM2.5 reaches 250μ g/m3, the AQI reaches 300; When the daily average concentration of PM2.5 reaches 500 μ g/m3, the corresponding AQI index reaches 500. The air pollution index is 0-50, the air quality level is Grade I, and the air quality status is excellent. 5 1 ~ 100 Grade II is good, 10 1 ~ 150 Grade III is light pollution, 15 1 ~ 200 Grade IV is moderate pollution, and 20/kloc-0. The United States imports Puweixin Tmall to prevent smog, go out to check the weather and take good protection. Protecting the environment is everyone's responsibility.