How to classify the air quality grade of daily weather forecast?

Common air quality grades are as follows:

Excellent grade (Grade A): The air quality index (AQI) is less than or equal to 50, which means that the air quality is excellent, there is no obvious irritation or weak air pollution, and there is no harm to public health.

Good grade (Grade B): AQI is between 5 1- 100, indicating that the air quality is good, and there is no obvious irritation or moderate air pollution, which has a slight impact on public health.

Intermediate (Grade C): AQI is between 10 1- 150, indicating that the air quality is moderate, with some irritation or slight pollution, and has a slight impact on public health.

Light pollution (Grade D): AQI is between 15 1-200, indicating that the air quality is light pollution, with strong irritation or light pollution, which has a certain impact on public health.

Heavy pollution (Grade E): AQI & gt200, indicating that the air quality is heavily polluted, irritating or heavily polluted, which has a great impact on public health.