Air Quality Index Calculator

The Air Quality Index Calculator estimates your current air quality level based on concentrations of PM2.5, PM10, Ozone, and other key pollutants. This tool helps health-conscious individuals and families understand environmental risks to make safer daily decisions. Whether you are planning outdoor exercise, checking safety for sensitive groups, or deciding on mask usage, this calculator provides immediate, actionable insights based on EPA standards.

Fine particulate matter (2.5 micrometers or smaller)
Inhalable particulate matter (10 micrometers or smaller)
8-hour average ozone concentration
Annual average nitrogen dioxide concentration
1-hour average sulfur dioxide concentration
8-hour average carbon monoxide concentration

How Air Quality Index Is Calculated

The Air Quality Index (AQI) translates complex pollution data into a simple, standardized score representing current air quality. This calculation relies on the EPA's piecewise linear interpolation method to map raw pollutant concentrations onto the 0-500 scale.

I_p = [(I_hi - I_lo) / (C_hi - C_lo)] × (C_p - C_lo) + I_lo

Where:

  • I_p = The AQI value for the pollutant
  • C_p = The pollutant concentration
  • C_hi, C_lo = The concentration breakpoints
  • I_hi, I_lo = The AQI index breakpoints
  1. The tool calculates a sub-index for each pollutant by finding where the concentration sits between established high and low breakpoints.
  2. It identifies the maximum sub-index among all pollutants to determine the final AQI.
  3. This "worst-case" approach ensures your score reflects the most significant health risk present.

By adhering to these established EPA breakpoints, this method provides a scientifically credible assessment of local air conditions for your safety.

What Your Air Quality Index Means

Your AQI score serves as a guide for protecting your health against airborne pollutants and making informed decisions about your outdoor activities.

General Health: An AQI of 0 to 50 is "Good," meaning air quality is satisfactory, and outdoor activities are safe for everyone. If the score is 51 to 100 ("Moderate"), air quality is acceptable, but unusually sensitive people should consider reducing prolonged exertion.

Sensitive Groups: An AQI of 101 to 150 indicates "Unhealthy for Sensitive Groups." At this level, children, the elderly, and those with asthma should limit time outdoors and reduce heavy exertion.

High Protection: When the AQI reaches 151 to 200 ("Unhealthy"), everyone may begin to experience health effects. You should reduce outdoor activities, and sensitive groups should avoid them entirely. Consider wearing an N95 mask if you must go outside.

Important: Air quality can change quickly based on weather, traffic, and time of day, so check local updates frequently for the most current data.

This tool is for informational purposes only and is not a substitute for professional medical advice. Always consult a healthcare provider for specific health concerns regarding air pollution exposure.

For the best safety, check the AQI forecast each morning and use an air purifier indoors when levels exceed 100.

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