AQHIis Canada's Air Quality Health Index. It is a health-based scale starting at 1, where higher means more risk to your health from breathing the air. It is the number Environment and Climate Change Canada uses (Alberta publishes its own AQHI readings too), and it is the number this site reports for each part of Calgary.
| AQHI | Risk | What to do |
|---|---|---|
| 1–3 | Low | Ideal for outdoor activity. |
| 4–6 | Moderate | Fine for most people. Consider easing off strenuous outdoor exercise if you have asthma, heart or lung conditions, or if you notice symptoms. |
| 7–10 | High | Reduce or reschedule strenuous outdoor activity. At-risk groups — children, older adults, anyone with respiratory or heart conditions — should avoid it. |
| 10+ | Very high | Everyone should avoid strenuous outdoor activity. At-risk groups should stay indoors where possible. |
Many weather sites and apps show a US-style AQI, a 0–500 scale usually driven by whichever single pollutant is worst — most often fine particulate matter (PM2.5). AQHI works differently: it combines ground-level ozone, nitrogen dioxide and PM2.5 into one health-risk figure, because the combination is what actually affects your lungs and heart.
This matters more than it sounds. On a hot, sunny, still Calgary afternoon, ozone can be the dominant problem while PM2.5 looks unremarkable. A PM2.5-only index will report "good" air on a day when the real AQHI is 5 and sensitive people are feeling it. That mismatch is exactly why this site computes proper AQHI from all three pollutants rather than converting a particulate reading.
The big one is wildfire smoke. Summer smoke drifting in from British Columbia or northern Alberta can push Calgary's AQHI into the high or very high bands for days at a time, and it is the most common reason for a genuinely bad air day here.
Otherwise, traffic and industry drive NO₂, concentrated near major routes and the downtown core. Winter brings a different mechanism: a temperature inversion during a cold snap traps pollutants near the ground, so still, frigid days can read worse than windy mild ones. A chinook, by contrast, usually clears the air out — see chinook winds explained.
Open the live map and click your community — the popup shows the AQHI with its risk band alongside the temperature and wind. Each district page carries the same reading.
One honest limitation: Environment Canada's official AQHI uses a three-hour rolling average of pollutants. This site uses the current hour, which is a close approximation but can differ by about a point. For health decisions during a wildfire smoke event, check Environment Canada's official AQHI as well.
Canada's Air Quality Health Index — a health-based scale starting at 1, computed from ozone, nitrogen dioxide and PM2.5 together. 1–3 is Low risk, 4–6 Moderate, 7–10 High, above 10 Very high.
No. The US-style AQI often reflects one dominant pollutant, while AQHI combines three. A PM2.5-only index can report 'good' air on a high-ozone day when the real AQHI is 5 and sensitive people are feeling it.
Calgary's AQHI usually sits in the Low range (1–3) most of the year. The exception is wildfire smoke season — smoke drifting in from B.C. or northern Alberta has pushed the city's official AQHI into the Moderate-to-High range for days at a time in past summers, well above what a calm-air day would suggest.