Air Quality (2)

What is AQI?

AQI, the full name is Air Quality Index, is a dimensionless index that quantitatively describes the air quality. Simply put, the AQI tells us how clean or polluted the air is, and the associated health effects.

How is the AQI calculated and evaluated?

The main pollutants involved in the evaluation of the air quality index are PM2.5, PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO) of inhalable particulate matter. Compared with the graded concentration limits of each pollutant (Table 1), the Air Quality Index (Individual Air Quality Index) is calculated by the measured concentration values of the six pollutants (among which PM2.5 and PM10 are the 24-hour average concentrations). , referred to as IAQI); select the maximum value from the IAQI of each pollutant to determine the AQI, when the AQI is greater than 50, determine the pollutant with the largest IAQI as the primary pollutant; compare the AQI classification standard (Table 2), determine the air quality levels, categories and indication colors, health effects and recommended actions.

How to use AQI?

The AQI is divided into six levels, ranging from level 1 good, level 2 moderate, level 3 unhealthy for sensitive groups, level 4 unhealthy, level 5 very unhealthy, and level 6 hazardous. Each level corresponds to a different health issue. At the same time, each level also has a specific color. This color makes it easy for people to quickly determine if air quality in their community is reaching unhealthy levels. When the characteristic color is green or yellow, the level is good or moderate, and the general population can do normal activities; when the characteristic color is orange or red, the level is unhealthy for sensitive groups or unhealthy, and susceptible people need to reduce outdoor activities; When the characteristic color is purple or maroon, the air pollution is serious, and all kinds of people need to pay attention to the recommended measures and use it as a reference when arranging their own life and travel.