What Does the AQHI Mean? Canada's Air Quality Health Index Explained
Understand Canada's AQHI scale from 1 to 10+, what low, moderate, high, and very high risk mean, and how wildfire smoke can change air-quality health risk quickly.
AQHI is a health-risk scale, not a smoke detector
Canada's Air Quality Health Index translates measured air pollution into a number intended to help people understand short-term health risk. The scale runs from 1 to 10+, with higher numbers representing greater health risk. It can be affected by wildfire smoke, but it also reflects other outdoor air pollutants.
- 1 to 3: low health risk.
- 4 to 6: moderate health risk.
- 7 to 10: high health risk.
- Above 10: very high health risk.
Wildfire smoke can make AQHI change rapidly
During smoky conditions, fine particulate matter known as PM2.5 can rise quickly. Federal AQHI guidance allows PM2.5 to drive the hourly reported health risk during wildfire smoke events, so the number may move faster than it does on an ordinary day.
Use the number together with your own symptoms and local guidance
The same AQHI value does not affect every person equally. Health conditions, age, pregnancy, outdoor work, exercise intensity, and other factors can change individual risk. Check official AQHI guidance for the health messages attached to the current category and follow local health advisories.
AQHI and FireRadar's smoke forecast answer different questions
AQHI is an observed and forecast health-risk indicator. FireRadar's FireWork layer is modelled wildfire-smoke PM2.5 guidance. Use the smoke forecast to understand where smoke may move, and AQHI or local monitoring to understand current health-risk conditions.
Common questions
Is AQHI the same as PM2.5?
No. AQHI is a health-risk index. PM2.5 is a pollutant measurement. During wildfire smoke events, very high PM2.5 can become the main driver of the hourly AQHI.
What does AQHI 10+ mean?
It is the highest AQHI health-risk category and indicates very high health risk. The displayed index stays at 10+ even though pollution concentrations can continue increasing.
Can the AQHI be poor when I cannot see smoke?
Yes. Fine particles are too small to see individually, and air quality can be affected even when smoke is not visually obvious.
Official and trusted sources
FireRadar summarizes these resources in plain language. Follow the source itself for the newest guidance, local instructions, eligibility rules, or operational decisions.
Explains the AQHI 1 to 10+ scale and how wildfire smoke can affect hourly AQHI reporting.
Current federal hub for wildfire smoke, AQHI, alerts, preparation, and health guidance.
Related FireRadar resources
Learn when a well-fitting N95 or equivalent respirator may help reduce wildfire-smoke particle exposure, what it cannot filter, and why fit matters.
Learn how wildfire-smoke PM2.5 can enter buildings, why indoor air is not automatically smoke-free, and how filtration and ventilation choices affect exposure.
Learn how to interpret official wildfire incidents, satellite hotspots, fire perimeters, smoke forecasts, AQHI, statuses, timestamps, and evacuation information without mixing unlike datasets.
Open province, territory, wildfire, hotspot, smoke, and AQHI map views from the FireRadar directory.