🌫️ Air Quality Index Calculator
Convert a raw PM2.5 or PM10 concentration reading into the standard 0-500 Air Quality Index scale and see its health category.
What This Calculator Does
This tool converts a raw pollutant concentration reading, in micrograms per cubic meter, into the standard 0-500 US Air Quality Index (AQI) scale used to communicate how clean or polluted the air is.
How the Formula Works
The AQI is calculated using the official EPA piecewise-linear breakpoint formula: AQI = ((I_high – I_low) / (C_high – C_low)) x (C – C_low) + I_low, where C is your measured concentration and C_low/C_high/I_low/I_high come from the breakpoint table for the selected pollutant. This calculator uses the EPA’s PM2.5 breakpoints (updated in 2024) and standard PM10 breakpoints, the two most commonly reported particulate pollutants in everyday air quality readings.
Reading the Result
An AQI of 0-50 is considered Good, 51-100 Moderate, 101-150 Unhealthy for Sensitive Groups, 151-200 Unhealthy, 201-300 Very Unhealthy, and above 300 Hazardous. Higher AQI values indicate a greater level of air pollution and a greater associated health concern.
Note: This calculator is for general educational and planning purposes only. It converts a single pollutant reading and does not replace official multi-pollutant AQI reports from local air quality monitoring agencies, nor is it medical or safety advice.