A CIESE Realtime Data Project

What's Your AQI? - Air Pollution: What's the Solution?

What's Your AQI?


Student Worksheet
AQI Equation
Breakpoints Table

  1. Obtain copies of the AQI Equation (.PDF) and Breakpoints Table (.PDF).
  2. Review the following examples to learn how to convert ozone ppm readings into an AQI value:
    1. 8-hour Ozone example
      Suppose you have an 8-hour ozone concentration of 0.0874125 ppm.  First you round off the concentration to 0.087 ppm.  Then look in the Breakpoints Table (.PDF) under the 8-hour ozone for the range of concentrations that contain this concentration (0.085 - 0.104 ppm). This range in the table for the 8-hour ozone corresponds to index values of 101 to 150. Now you have all the numbers needed to use the AQI equation:

      Where IP = the index for pollutant P  
      CP = the rounded concentration of pollutant P        
      BPHi = the breakpoint that is greater than or equal to CP 
      BPLo = the breakpoint that is less than or equal to CP       
      IHi = the AQI value corresponding to BPHi   
      ILo = the AQI value corresponding to BPLo

      So, an 8-hour concentration of 0.0874125 ppm corresponds to an AQI value of 106.

    2. Multiple Pollutants example
      Suppose you have an 8-hour ozone value of 0.077 ppm, a PM2.5 value of 54.4μg/m3, and a CO value of 8.4 ppm.  You apply the equation 3 times:
       - For Ozone (O3):
       - For Particulate Matter (PM2.5):
       - For Carbon Monoxide (CO):
      • The AQI is 128 with PM2.5 as the responsible pollutant.
  3. Complete the problems on the Student Worksheet.

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