Greater Toronto Air Quality & AQHI Observatory
Measured fine particulate matter (PM2.5), ground-level ozone (O3), and nitrogen dioxide (NO2) with the Air Quality Health Index across the Greater Toronto Area.
Health Notice: Enjoy your usual outdoor activities.
Low risk at Milton. Weather: No alerts at last check, 12:30 a.m. ET.
Air Quality Health Index
At-Risk Population
Enjoy your usual outdoor activities.
General Population
Enjoy your usual outdoor activities.
Observed Nov 9, 11:00 p.m. ET
PM2.5 Fine Particulate
Aerodynamic ≤ 2.5 µm
O3 Ground Ozone
Tropospheric oxidant
NO2 Nitrogen Dioxide
Traffic & thermal plume
48-Hour Timeline & 24-Hour Predictive Curve
Observed readings from the past 48 hours through the current hour into Environment Canada's 24-hour forecast.
Reached 4 on Nov 8, 9:00 p.m. ET.
AQHI 2. Fine particles 3 µg/m³.
Index 2 forecast for Nov 10, 1:00 a.m. ET.
Cross-Regional GTA Monitoring Stations
Comparative readings from Ontario Ministry (MECP) and federal monitoring sites across the region.
| Monitoring Station | AQHI Index | PM2.5 (µg/m³) | O3 (ppb) | NO2 (ppb) | Health Risk Category | Trend Sparkline |
|---|---|---|---|---|---|---|
TorontoMetro Region | 2 | 5 µg/m³ | 11 ppb | 17.2 ppb | Low Risk (1-3) | |
Toronto NorthYork Region | 2 | 3 µg/m³ | 16 ppb | 8.9 ppb | Low Risk (1-3) | |
Toronto EastDurham Region | 2 | 3 µg/m³ | 17 ppb | 7.8 ppb | Low Risk (1-3) | |
Toronto WestMetro Region | – | 7 µg/m³ | 11 ppb | 15.3 ppb | – | |
MississaugaPeel Region | 2 | 3 µg/m³ | 17 ppb | 6 ppb | Low Risk (1-3) | |
BramptonPeel Region | 1 | 3 µg/m³ | 18 ppb | 3.6 ppb | Low Risk (1-3) | |
OakvilleHalton Region | 2 | 3 µg/m³ | 20 ppb | 4 ppb | Low Risk (1-3) | |
BurlingtonHalton Region | 2 | 3 µg/m³ | 17 ppb | 6.7 ppb | Low Risk (1-3) | |
MiltonHalton Region | 2 | 3 µg/m³ | 19 ppb | 4.7 ppb | Low Risk (1-3) | |
NewmarketYork Region | 1 | 2 µg/m³ | 20 ppb | 3.5 ppb | Low Risk (1-3) | |
OshawaDurham Region | 1 | 2 µg/m³ | 19 ppb | 3.3 ppb | Low Risk (1-3) |
The Health Risk Calculation Model
Canada's AQHI combines a 3-part pollutant mixture rather than reporting the worst single reading:
About These Readings
The index comes from Environment and Climate Change Canada. Pollutant readings are from Air Quality Ontario, whose figures are automatically polled and have not undergone final verification.
The percentage bars compare a reading with the Canadian standard for that pollutant as a guide. The standards apply over longer periods than one hour.
Official Advice By Risk Level
- 1-3: Enjoy your usual outdoor activities.
- 4-6: Consider reducing or rescheduling strenuous outdoor activities if you have symptoms like coughing or throat irritation.
- 7+: Reduce or reschedule strenuous outdoor activities.
Data Source: Environment and Climate Change Canada. Licence. Pollutant readings: Ministry of the Environment, Conservation and Parks, Air Quality Ontario. Shown as published and may be out of date. This is not a warning service. IGTA is not affiliated with or endorsed by either government.
Milton
MiltonLow Health Risk
Enjoy your usual outdoor activities.
Enjoy your usual outdoor activities.
24h running mean: 1.8 µg/m³
Photochemical generation
Canadian 1h standard: 60 ppb
Measured Nov 9, 11:00 p.m. ET
GTA Regional Stations
Sorted by AQHI
Multi-Pollutant Cumulative Health Risk
The Canadian AQHI evaluates the combined health risk of three pollutants (O₃, PM₂.₅, and NO₂) rather than reporting the worst single reading.
About These Readings
Index from Environment and Climate Change Canada. Licence. Pollutants from Air Quality Ontario, automatically polled and not finally verified. Shown as published and may be out of date. This is not a warning service.