AQI Equation
Where
Conci = Input concentration for a given pollutant
ConcLo = The concentration breakpoint that is less than or equal to Conci
ConcHi = The concentration breakpoint that is greater than or equal to Conci
AQILo = The AQI value/breakpoint corresponding to ConcLo
AQIHi = The AQI value/breakpoint corresponding to ConcHi
Rounding vs. Truncating
For all AQI calculations, the calculated average concentrations are truncated to .001 ppm (1 ppb) for O3, 0.1 μg/m3 for PM2.5, and 1 μg/m3 for PM10. This truncated concentration is then used as the input (Conci) in the AQI equation above. The resulting AQI is rounded to the nearest whole number
