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Calculate AQI from pollutant concentrations with EPA breakpoints and health guidance.
The Air Quality Index is a numerical scale from 0 to 500 used by the U.S. EPA to communicate daily air pollution levels and associated health risks.
Formula
AQI = piecewise linear interpolation from pollutant concentration breakpointsCp = Truncated pollutant concentration
BPHi/BPLo = Concentration breakpoints bounding Cp
IHi/ILo = AQI values corresponding to breakpoints
Worked Example
PM2.5 concentration of 35.5 µg/m³
Did you know? The EPA estimates that the Clean Air Act has prevented over 230,000 early deaths annually in the U.S. since its enactment in 1970 (source: U.S. EPA).
Sources
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