Information about AQI

The air quality index is a dimensionless value, calculated from information from the existing legislation relating to the air pollutants that are modeled. Its main objective is to facilitate the understanding of information related to air pollution.

AQI's values are between 0 and >150, so that the greater values mean worse air quality.

At the qualitative level, the AQI values are divided into four ranges:

  • Good: GREEN (AQI 0 to 50)
  • Permissible: YELLOW (AQI 50 to 100)
  • Bad: RED (AQI 100 to 150)
  • Very bad: BROWN (AQI >150)

AQI legend

In the case of PRESAXIO forecasting model, for each day is calculated the ICA of each cell of the grid, following the next process:

  • From the data of the modeling, is determined the maximum hourly concentration of each pollutant in each cell.
  • Are assigned the value of partial index ​​of each pollutant for these concentrations (partial index value 0 corresponds to a zero concentration of pollutant; the value 100 is associated with each limit value of the pollutant; the index value for any value of concentration is obtained by linear interpolation).
  • Is selected the maximum value of partial index, which is taken as the index value of the cell.
  • The cell is shown in the color associated with the index that has been obtained.

Thus, if the index is greater than 100 (RED), will have exceeded the limit value of at least one of the modeled pollutants.

For guidance in preparing this Air Quality Index, it has taken as reference the document of the working group "INFORMATION TO THE PUBLIC ON AIR POLLUTION. AIR QUALITY INDEX ", presented at the Fourth Seminar on Air Quality Spain (Sitges, 2000).