The air quality index is generally divided into six grades: 0-50, 50- 100, 100- 150, 150-200, 200-300, 300-500.

An air quality index of 0-50 indicates excellent air quality. At this time, the air quality is satisfactory, there is basically no air pollution, and all kinds of people can move normally.

The air quality index is 5 1- 100, indicating good air quality. At this time, the air quality is acceptable, but some pollutants in the air may have a slight impact on the health of a few extremely sensitive people. It is suggested that a few extremely sensitive people reduce outdoor activities.

The air quality index is 150, indicating that the air quality is slightly polluted. At this time, the symptoms of susceptible people are slightly aggravated, and healthy people have irritating symptoms. It is suggested that children, the elderly and patients with heart disease and respiratory diseases should reduce long-term and high-intensity outdoor sports.

The air quality index is 15 1-200, indicating that the air quality is moderately polluted. At this time, further aggravating the symptoms of susceptible people may have an impact on the heart and respiratory system of healthy people. Therefore, it is suggested that patients with diseases should avoid long-term and high-intensity outdoor exercise, and the general population should moderately reduce outdoor exercise.