Technical Assistance Document for the Reporting of Daily Air Quality — the Air Quality Index (AQI)

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The AQI is the highest value calculated for each pollutant as follows: 1. Identify the highest concentration among all of the monitors within each reporting area and truncate as follows: Ozone (ppm) – truncate to 3 decimal places PM2.5 (µg/m3) – truncate to 1 decimal place PM10 (µg/m3) – truncate to integer CO (ppm) – truncate to 1 decimal place SO2 (ppb) – truncate to integer NO2 (ppb) – truncate to integer 2. Using Table 6 (next page), find the two breakpoints that contain the concentration. 3. Using Equation 1, calculate the index. 4. Round the index to the nearest integer. Equation 1: I Hi − I Lo (C − BPLo ) + I Lo . Ip = BPHI − BPLo p Where Ip = the index for pollutant p Cp = the truncated concentration of pollutant p BPHi = the concentration breakpoint that is greater than or equal to Cp BPLo = the concentration breakpoint that is less than or equal to Cp IHi = the AQI value corresponding to BPHi ILo = the AQI value corresponding to BPLo

Referencing norms: co, no2, o3, pm10, pm25, so2