Canadian Air Quality Health Index
Canada AQHI Calculator
Calculate the standard Canadian Air Quality Health Index from three-hour rolling averages of ozone, nitrogen dioxide, and PM2.5. See the 1–10+ risk level and how much each pollutant contributes to the formula.
Calculate Canada's three-pollutant AQHI
Use three-hour rolling averages for all inputs. Ozone and nitrogen dioxide are entered in ppb; fine particles are entered in µg/m³.
Air Quality Health Index
1–3
4–6
7–10
10+
- Unrounded formula result
- 6.1
- Displayed category
- 6
Formula contribution
This is the standard three-pollutant AQHI formula. AQHI and U.S. AQI measure risk differently, so this tool does not perform a one-to-one conversion or apply a wildfire adjustment.
How the Canadian AQHI is calculated
- The standard AQHI combines exponential mortality-risk terms for O₃, NO₂, and PM2.5, then multiplies their sum by 1000 ÷ 10.4.
- Ozone and nitrogen dioxide inputs are three-hour rolling means in ppb; PM2.5 is a three-hour rolling mean in µg/m³.
- The formula result is rounded to the nearest integer, displayed from 1 through 10+, and grouped into low, moderate, high, or very high risk.
- Contribution bars split the calculated formula total; they do not imply that the same percentage of every individual's health risk comes from each pollutant.
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.
U.S. multi-pollutant AQI calculator
Calculate AQI sub-indices for ozone, particles, carbon monoxide, sulfur dioxide, and nitrogen dioxide.
PM NowCast calculator
Turn the latest 12 hourly PM2.5 or PM10 readings into an EPA-weighted NowCast and AQI.
Indoor PM2.5 calculator
Estimate steady-state indoor PM2.5 from outdoor air, room volume, infiltration, sources, and purifier CADR.
Trust Signals
Use official three-hour means and local Canadian guidance
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.
Canadian AQHI questions
Is AQHI the same as U.S. AQI?
No. AQHI combines the health risk of three pollutants in one formula, while U.S. AQI reports the highest pollutant sub-index. A one-to-one conversion is not scientifically sound.
Why does the lowest result display as 1?
Canada communicates AQHI on a public scale beginning at 1. The calculator still shows the unrounded formula value for transparency.
What does 10+ mean?
Values above 10 are communicated as 10+ and classified as very high risk.
Does this include the wildfire-adjusted AQHI?
No. This first version implements only the fully documented standard three-pollutant formula and does not infer a wildfire adjustment.