Toronto Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (10 October): Air quality in Toronto is good. AQI, PM2.5, PM10, NO2, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 1:00 PM (PM2.5: 19.7/100).
Air Quality Tomorrow
Tomorrow (11 October 2026): Air quality in Toronto is fair. AQI worsens to fair; PM2.5 increases to fair; NO2 increases to fair; all other pollutants stay as today. Pollution peaks around 3:00 PM (NO2: 35.0/100).
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Air Quality
Today - 10 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Good | 19.7/100 |
| PM2.5 (fine particles) | Good | 19.7/100 |
| PM10 (coarse particles) | Good | 14.4/100 |
| NO2 (nitrogen dioxide) | Good | 17.8/100 |
| O3 (ozone) | Good | 14.4/100 |
| SO2 (sulfur dioxide) | Good | 0.9/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 2.0/100 |
| PM1 (ultrafine particles) | Good | 7.1/100 |
Tomorrow - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 35.0/100 |
| PM2.5 (fine particles) | Fair | 20.3/100 |
| PM10 (coarse particles) | Good | 12.8/100 |
| NO2 (nitrogen dioxide) | Fair | 35.0/100 |
| O3 (ozone) | Good | 14.0/100 |
| SO2 (sulfur dioxide) | Good | 0.3/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 1.6/100 |
| PM1 (ultrafine particles) | Good | 8.0/100 |
Local Environmental Conditions
Air pollution in Toronto comes mainly from traffic. Highway 401, one of the busiest highways in North America, the Gardiner Expressway and the Don Valley Parkway carry heavy traffic, and neighbourhoods along these routes see the highest levels of nitrogen dioxide and fine particles. Pearson Airport and industry in the surrounding region add to the mix. Some pollution also drifts in from the US Midwest, while breezes off Lake Ontario often help clear the air downtown. The worst days now come from wildfire smoke.
Toronto's air quality changes with the seasons. From June to August, hot, sunny days can raise ozone, especially when winds carry pollution north from the United States. Wildfire smoke has become a recurring summer problem: on July 15, 2026, smoke from fires in northwestern Ontario gave Toronto the worst air quality of any major city in the world, with the index at its highest level and outdoor events cancelled. In winter, cold, still mornings, averaging around -4°C in January, can trap traffic pollution near the ground.
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Frequently Asked Questions About Air Quality in Ontario
Is air quality bad in Toronto right now?
On 10 October 2026, overall air quality in Toronto is good. AQI is the main air quality indicator at 19.7/100. Pollution peaks around 1:00 PM (PM2.5: 19.7/100).
Will air quality be worse tomorrow in Toronto?
On 11 October 2026, air quality conditions in Toronto will be worse than today, with AQI forecast at fair at 35.0/100. Pollution peaks around 3:00 PM (NO2: 35.0/100).
When is air pollution at its worst in Toronto?
Toronto's air quality changes with the seasons. From June to August, hot, sunny days can raise ozone, especially when winds carry pollution north from the United States. Wildfire smoke has become a recurring summer problem: on July 15, 2026, smoke from fires in northwestern Ontario gave Toronto the worst air quality of any major city in the world, with the index at its highest level and outdoor events cancelled. In winter, cold, still mornings, averaging around -4°C in January, can trap traffic pollution near the ground.
Are air quality levels in Toronto based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
Understanding the Scale
The 0–100 air quality scores represent risk levels, not direct air pollutant concentrations. Higher scores indicate higher risk.
Air Quality
| Good | 0-20 | Low air quality risk. Air quality is expected to be good, with low levels of pollution. |
| Fair | 20-40 | Generally low air quality risk. Air quality is expected to be acceptable, with some pollution present. |
| Moderate | 40-60 | Moderate air quality risk. Air pollution is elevated and air quality may be less favorable. |
| Poor | 60-80 | High air quality risk. Air pollution is high and air quality is expected to be poor. |
| Very Poor | 80-100 | Very high air quality risk. Air pollution is very high and air quality is expected to be very poor. |