Short answer. Canada's official measure is the Air Quality Health Index (AQHI), a scale from 1 to 10+ that you can check for your location on weather.gc.ca or in the WeatherCAN app 1. At 7 or more (high risk), children, people over 65 and people with health conditions should reduce or reschedule strenuous outdoor activities 1. If a wildfire threatens your community, follow local authorities and be ready to evacuate 2.
Where can I check air quality in Canada right now?
Select your location on the local AQHI page at weather.gc.ca, or use the WeatherCAN app 1. Health Canada also points to air quality alerts and wildfire smoke forecast maps on weather.gc.ca, InfoSmog forecasts for Québec, and most provincial and territorial government websites; WeatherCAN can notify you when the AQHI changes 2.
What do the AQHI levels mean?
The AQHI is calculated from ground-level ozone, fine particles (PM2.5/PM10) and nitrogen dioxide; during wildfire smoke events, only PM2.5 is used for the hourly value 1. The official advice 1:
| AQHI | Risk | People at risk | General population |
|---|---|---|---|
| 1-3 | Low | Enjoy usual outdoor activities | Enjoy usual outdoor activities |
| 4-6 | Moderate | Consider reducing or rescheduling strenuous outdoor activities if you have symptoms | Usual outdoor activities unless you have symptoms such as coughing or throat irritation |
| 7-10 | High | Reduce or reschedule strenuous outdoor activities | Consider reducing or rescheduling strenuous outdoor activities if you have symptoms |
| 10+ | Very high | Avoid strenuous activities outdoors | Reduce or reschedule strenuous outdoor activities, especially if you have symptoms |
"People at risk" means children, people over 65 and people with health conditions 1. See also air quality index.
How polluted is Canadian air on average?
Annual fine particles (PM2.5) in the median Canadian city were about 8 µg/m³ in 2021-2023, against a WHO guideline of 5 µg/m³ 35. Nitrogen dioxide (NO2) was about 8.4 µg/m³, under the WHO guideline of 10 µg/m³ 45. These are population-weighted medians across 2,711 cities; the NO2 figure is a regional background over roughly 80 km, so a busy street is higher.
How do I prepare for wildfire smoke?
Health Canada's preparation list 2:
- Talk to your doctor before the season if you are in a higher-risk group, and keep a supply of your medications.
- Know how to reach your local health authority for nearby cleaner air spaces.
- Have well-fitting NIOSH-certified N95 or equivalent respirators (KN95 or KF94 are also listed).
- Seal windows and doors; clean or replace ventilation filters, using the highest-quality filter your system can handle, and keep spares.
- Consider a portable air cleaner sized for the room, which can filter fine smoke particles.
- Check that carbon monoxide alarms work, and change your vehicle's cabin air filter regularly.
If a wildfire threatens your community, your local health or emergency authorities will provide direction; if told to evacuate, do so immediately 2. See wildfire smoke, masks for smoke, clean air room and children and polluted air. Your household plan can list who is at risk and where your cleaner air space is.
Frequently asked questions
What AQHI number is dangerous?
The AQHI defines 7 to 10 as high risk and above 10 as very high risk. At 10+, people at risk should avoid strenuous outdoor activity 1.
Why does the AQHI only use PM2.5 during wildfires?
Environment and Climate Change Canada states that during wildfire smoke events only PM2.5 is used to calculate the hourly AQHI 1.
Can I get air quality alerts on my phone?
Yes. The WeatherCAN app can send notifications when the AQHI changes 2.
Does Québec use a different system?
Yes. Environment and Climate Change Canada states that all of Canada uses the AQHI except Québec, which uses the Info-Smog program 1; Health Canada points to InfoSmog forecasts for Québec 2.
Sources
- Environment and Climate Change Canada (Canada.ca) — About the Air Quality Health Index — https://www.canada.ca/en/environment-climate-change/services/air-quality-health-index/about.html (accessed 2026-10-27)
- Health Canada (Canada.ca) — Preparing for wildfire smoke events — https://www.canada.ca/en/health-canada/services/publications/healthy-living/how-prepare-wildfire-smoke.html (accessed 2026-10-27)
- Atmospheric Composition Analysis Group (ACAG), Washington University in St. Louis — Surface PM2.5, V6.GL.02.04 — https://sites.wustl.edu/acag/datasets/surface-pm2-5/ (accessed 2026-10-27)
- Copernicus Atmosphere Monitoring Service — CAMS global reanalysis (EAC4) — https://ads.atmosphere.copernicus.eu/ (accessed 2026-10-27)
- World Health Organization — WHO global air quality guidelines — https://www.who.int/publications/i/item/9789240034228 (accessed 2026-10-27)
Turn this into action
Your plan for Canada, worked out for your household.
- Water, food and equipment counted for each person and pet
- The nuclear plants and zones around your home
- Phaenyx Safe: one tap to tell your people you are safe
Sources
- Environment and Climate Change Canada (Canada.ca) · About the Air Quality Health Index checked 2026-10-27
- Health Canada (Canada.ca) · Preparing for wildfire smoke events checked 2026-10-27
- Atmospheric Composition Analysis Group (ACAG), Washington University in St. Louis · Surface PM2.5, V6.GL.02.04 checked 2026-10-27
- Copernicus Atmosphere Monitoring Service · CAMS global reanalysis (EAC4) checked 2026-10-27
- World Health Organization · WHO global air quality guidelines checked 2026-10-27