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Air Quality Index (AQI)

The Air Quality Index is a measurement of outdoor air quality where you live. It provides information on whether or not the air is polluted and on any health impacts.

The air quality index and the main pollutant in the air are displayed in the app.

How does the AQI work?

The AQI can be calculated for the five main pollutants regulated by the Clean Air Act: ground-level ozone (O3), particulate pollution (also known as particulate matter, PM2.5 and PM10), carbon monoxide (CO), sulphur dioxide (SO2) and nitrogen dioxide (NO2).

The Air Quality Index is made up of a value from 0 to 500 and a level of health concern ranging from good to hazardous.

AQI measurements Levels of Health Concern Meaning
0 à 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk.
51 à 100 Moderate Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
101 à 150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected.
151 à 200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
201 à 300 Very Unhealthy Health alert: everyone may experience more serious health effects.
301 à 500 Hazardous Health warnings of emergency conditions. The entire population is more likely to be affected.


We use the data provider AerisWeather for all air quality data. Data are based on the AirNow standard.

For more information on the AirNow standard, you can visit this page (available in English and Spanish):


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