Six-pollutant U.S. AQI calculator
U.S. Multi-Pollutant AQI & Concentration Calculator
Calculate individual AQI sub-indices for ozone, PM2.5, PM10, carbon monoxide, sulfur dioxide, and nitrogen dioxide. See the overall AQI and primary pollutant, or reverse one AQI sub-index into its concentration band.
Calculate the AQI across six criteria pollutants
Use concentration averages that already match each pollutant's reporting period, or reverse one AQI sub-index into its concentration band.
Overall U.S. AQI
- Primary pollutant
- O₃
- Sub-indices calculated
- 6
U.S. AQI scale
| Pollutant | Used | AQI |
|---|---|---|
| O₃ | 0.078 ppm | 126 |
| PM2.5 | 22.4 µg/m³ | 76 |
| PM10 | 48 µg/m³ | 44 |
| NO₂ | 18 ppb | 17 |
| CO | 0.8 ppm | 9 |
| SO₂ | 5 ppb | 7 |
Overall AQI is the highest valid pollutant sub-index. PM2.5 and PM10 inputs here are 24-hour averages; use the PM NowCast calculator for recent hourly particle readings.
How the multi-pollutant AQI calculation works
- Each concentration is truncated using its pollutant-specific EPA convention before linear interpolation between published AQI breakpoints.
- The overall AQI is the highest valid pollutant sub-index. If two pollutants share the maximum, both are reported as primary pollutants.
- Ozone uses the applicable 8-hour and high-range 1-hour tables; sulfur dioxide uses the applicable 1-hour and high-range 24-hour tables.
- Reverse calculations are limited to AQI bands explicitly defined for the selected pollutant and averaging period; the tool does not bridge undefined bands.
Air quality tools for the decision in front of you
Start with the number or question you already have. Every tool leads to a concrete calculation, comparison, or action plan instead of another generic article.
PM NowCast calculator
Turn the latest 12 hourly PM2.5 or PM10 readings into an EPA-weighted NowCast and AQI.
PurpleAir EPA correction calculator
Correct a PurpleAir CF=1 PM2.5 reading for humidity, including extreme-smoke conditions.
Canada AQHI calculator
Calculate the Canadian Air Quality Health Index from three-hour ozone, NO₂, and PM2.5 averages.
Trust Signals
Use matching averaging periods and locally validated measurements
Review policy
August 8, 2026. We update supporting pages when calculator logic, live data behavior, or source framing changes.
Primary sources
AQI uses EPA / AirNow breakpoint logic. Cigarette-equivalent framing follows Berkeley Earth’s PM2.5 interpretation.
Live data layer
City pages use EPA AirNow where supported, with cached fallbacks and planning baselines if the API fails or coverage is unavailable.
Multi-pollutant AQI questions
Which pollutant determines the overall AQI?
The pollutant with the highest valid sub-index determines the overall U.S. AQI. Equal maximum sub-indices are shown as tied primary pollutants.
Can I enter a current PM2.5 sensor reading?
This page expects a 24-hour PM2.5 concentration for daily AQI reporting. Use the PM NowCast calculator with recent hourly readings when you need a current particle estimate.
Why is an AQI-to-concentration result unavailable for some pollutants?
EPA reporting tables do not define every AQI band for every averaging period. The calculator refuses to extrapolate through those gaps.
Does this calculate cigarette equivalents?
No. This page reports pollutant sub-indices, overall AQI, and the primary pollutant only. The site's existing exposure calculators remain separate.