Two-way U.S. EPA converter
PM2.5 ↔ AQI converter
Convert PM2.5 concentration in µg/m³ to U.S. AQI, or estimate concentration from a PM2.5 AQI. An overall AQI driven by another pollutant cannot be converted to PM2.5.
Estimated PM2.5
55.4 µg/m³
Category
Unhealthy for Sensitive Groups
Berkeley Earth 24-hour health-impact estimate
≈ 2.52 cigarette-equivalents
Interpolation band
AQI 101–150 / PM2.5 35.5–55.4 µg/m³
AQI-to-PM2.5 is an inverse estimate inside the relevant EPA breakpoint band; AQI itself is a rounded index.
Only use the comparison when AQI is specifically for PM2.5. It is a rough population-level health-impact estimate, not particle mass, inhaled dose, cigarettes smoked, personal risk, or diagnosis.
Technical reference: EPA PM2.5 AQI — May 2026 · Calculation reviewed: 2026-08-08
PM2.5 AQI breakpoints effective in 2024
PM2.5 breakpoints effective May 6, 2024; method documented in EPA/AirNow guidance, May 2026. EPA update. Page checked: .
| AQI | PM2.5 (µg/m³) |
|---|---|
| 0–50 | 0.0–9.0 |
| 51–100 | 9.1–35.4 |
| 101–150 | 35.5–55.4 |
| 151–200 | 55.5–125.4 |
| 201–300 | 125.5–225.4 |
| 301–500 | 225.5–325.4 |
Above AQI 500 (325.4 µg/m³), the category remains Hazardous. This tool extends the 301–500 line to AQI 700 and marks the result as an extrapolation outside the standard display scale.
Calculation method
For PM2.5 → AQI, concentration is truncated to one decimal, linearly interpolated inside its breakpoint band, then AQI is rounded to the nearest integer. The inverse direction estimates concentration from a rounded index.
Technical reference: EPA PM2.5 AQI — May 2026 · Calculation reviewed: 2026-08-08
EPA/AirNow technical guidance (May 2026)Trust Signals
Limits of AQI conversion
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.
Conversion questions
Can overall AQI be converted to PM2.5?
Only if the reported pollutant is PM2.5. Overall AQI may be driven by ozone or another pollutant.
What happens above AQI 500?
Values above 500 remain Hazardous. This tool extends the 301–500 PM2.5 line with the same slope through AQI 700, labels those results as extrapolations, and displays >700 when the concentration exceeds its extended range.
Why does 9.09 become 9.0?
EPA requires PM2.5 concentration to be truncated, not rounded, to one decimal before calculating AQI.