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🌍 US AQI Calculator

EPA Standard Air Quality Index Calculator

µg/m³
µg/m³
µg/m³
ppb
ppm
ppb

Enter pollutant values and click Calculate

📐 EPA AQI Formula

The AQI for each pollutant is calculated using:

AQI = [(IHigh - ILow) / (CHigh - CLow)] × (C - CLow) + ILow

Where:

  • C = Measured pollutant concentration
  • CLow = Concentration breakpoint ≤ C
  • CHigh = Concentration breakpoint ≥ C
  • ILow = AQI value corresponding to CLow
  • IHigh = AQI value corresponding to CHigh

The final AQI is the maximum of all individual pollutant AQIs.

AQI Categories

Good 0-50
Moderate 51-100
Unhealthy for Sensitive 101-150
Unhealthy 151-200
Very Unhealthy 201-300
Hazardous 301-500