How is the value of pm2.5 calculated in the weather forecast?

I don't know whether you are talking about the weather forecast on the internet or on TV.

The value is generally AQI, which refers to the air quality index, and PM2.5 is the main pollutant.

Or the average concentration of PM2.5, how many micrograms per cubic meter. There is a circle symbol behind the air quality.

According to the Technical Specification for Ambient Air Quality Index (HJ 633-20 12), the air pollution index is divided into 0-50, 5 1- 100,1-65438+. [2]

The air pollution index is 0-50, the air quality level is Grade I, and the air quality status is excellent. At this time, the air quality is satisfactory, there is basically no air pollution, and all kinds of people can move normally. [2]

The air pollution index is 5 1- 100, and the air quality grade is Grade II, so the air quality is in good condition. At this time, the air quality is acceptable, but some pollutants may have a weak impact on the health of a very small number of abnormally sensitive people. It is suggested that a very small number of extremely sensitive people reduce outdoor activities. [2]

The air pollution index is 10 1- 150, and the air quality grade is Grade III, so the air quality status belongs to mild pollution. 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. [2]

The air pollution index is 15 1-200, and the air quality grade is grade 4, so the air quality status belongs to moderate pollution. At this time, further aggravating the symptoms of susceptible people may have an impact on the heart and respiratory system of healthy people. 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. [2]

The air pollution index is 20 1-300, the air quality grade is 5, and the air quality is heavily polluted. At this time, the symptoms of patients with heart disease and lung disease are obviously aggravated, and the exercise tolerance is reduced, and the symptoms are common in healthy people. It is suggested that children, the elderly and patients with heart disease and lung disease stay indoors and stop outdoor sports, and the general population should reduce outdoor sports. [2]

The air pollution index is greater than 300, the air quality level is 6, and the air quality is seriously polluted. At this time, the exercise tolerance of healthy people is reduced, the symptoms are obviously strong, and some diseases appear in advance. It is suggested that children, the elderly and patients should stay indoors as much as possible to avoid physical exertion, and the general population should try to avoid outdoor activities. The United States imported Puwei Xintianmao.