AQHI to AQI Converter - Air Quality Index Converter
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Based on PM₂.₅ concentration of
The AQHI formula combines health risks from PM₂.₅, ozone (O₃), and nitrogen dioxide (NO₂). Even if PM₂.₅ stays the same, higher O₃ or NO₂ levels raise the AQHI's "baseline" risk. Adjust the sliders below to see how they affect the conversion. Default values represent typical urban background air levels.
This converter is for educational purposes only. Actual AQHI and AQI values depend on real-time measurements of multiple pollutants. The conversion assumes background O₃ and NO₂ levels and should not be used for health decisions.
Free bidirectional converter between AQHI (Canada's Air Quality Health Index) and AQI (US EPA Air Quality Index) using PM2.5 as the common reference. Supports both AQHI to AQI and AQI to AQHI conversion with the underlying PM2.5 concentration displayed.
How It Works
AQHI (Air Quality Health Index)
Canada's AQHI is a health-based index measuring the combined risk of PM2.5, ozone, and nitrogen dioxide on a scale from 1 to 10+. It uses a formula based on the excess mortality risk of each pollutant to indicate health risk.
AQI (Air Quality Index)
The US EPA AQI ranges from 0 to 500 across six color-coded categories. Linear interpolation within breakpoint ranges converts pollutant concentrations to an index value. Higher values mean greater health concern.
PM₂.₅ as the Bridge
PM2.5 (fine particulate matter) serves as the common reference between AQHI and AQI. We assume typical background O₃ (30 ppb) and NO₂ (20 ppb) for AQHI. This provides an approximate equivalent — actual indices use real-time multi-pollutant measurements.
Risk Level Guide
FAQ
Why doesn't this match official readings?
Official AQHI and AQI use real-time multi-pollutant data. This converter uses PM2.5 only and assumes background levels for O₃ and NO₂. For accurate readings, check your local air quality monitoring agency.
What are the limitations?
This assumes background O₃ (30 ppb) and NO₂ (20 ppb) for AQHI, and uses the 24-hour PM2.5 AQI breakpoints. Actual indices use real-time measurements of multiple pollutants. Local conditions may vary.
How does adjusting O₃ and NO₂ affect the results?
The AQHI formula includes health risks from PM₂.₅, O₃, and NO₂ together. When you increase O₃ or NO₂, the AQHI's "baseline risk" goes up — even if PM₂.₅ hasn't changed, the AQHI will be higher. Try this: keep the PM₂.₅ value fixed and drag the O₃ slider to watch the AQHI change in real time.
If I set O₃ and NO₂ to 0, is that more accurate?
Setting O₃ and NO₂ to 0 makes the AQHI reflect only PM₂.₅'s contribution, but this doesn't mean real air has zero ozone or nitrogen dioxide. Urban air always contains trace amounts of these gases — the default values (30 ppb O₃, 20 ppb NO₂) represent typical urban background levels. Setting them to 0 is useful for "what-if" analysis: it lets you see how much PM₂.₅ alone contributes to the AQHI.
What's the difference between AQHI and AQI?
AQHI (Canada's Air Quality Health Index) is a 1–10+ health risk index that tells you how air quality affects your health. AQI (the US Air Quality Index) is a 0–500 scale that focuses more on pollution level. They use different formulas: AQHI is exponential (more pollutants = each additional unit has a bigger health impact), while AQI is piecewise linear. This is why the same PM₂.₅ concentration may produce different trends in the two indices.
Can I use this tool for health decisions?
No. This tool is for learning how AQHI and AQI relate to each other and how O₃/NO₂ affect the conversion. Real air quality assessment requires real-time monitoring data. Please check official sources like AirNow (US) or Environment Canada AQHI for accurate information.