Air Quality Ontario

The quality of our air directly impacts our health and the natural environment, so we want our air to be as clean as possible. The Ministry of the Environment works to protect and improve air quality through legislation, targeted programs, and partnerships with other jurisdictions.

The ministry has a network of 40 ambient (outside) air monitoring stations across the province that collect real-time air pollution data. This information is communicated to the public through Ontario's Air Quality Index (AQI) and as hourly concentrations of each pollutant. The AQI and data collected from these 40 locations are posted on this website every hour, 24 hours a day, seven days a week. Each year, the ministry prepares an Air Quality Report to assess the state of air quality in Ontario based on the AQI network.


Today's Forecast: Good to Moderate Air Quality Expected

Forecast Summary: Air quality indices are forecast to be mainly in the good category across the province during Friday and in the good to moderate categories during Saturday and Sunday. For more details, see the Weather Forecast and the Air Quality Forecast.


Air Quality Index (AQI) Current AQI Readings

Hourly AQI Reports: The AQI is issued hourly and is an indicator of ambient air quality based on the following pollutants in our air: Ozone (O3), Fine Particulate Matter (PM2.5), Nitrogen Dioxide (NO2), Carbon Monoxide (CO), Sulphur Dioxide (SO2), and Total Reduced Sulphur (TRS) Compounds. What is the AQI?.


Pollutant Concentrations: Local, Live and Historical Data

Real-Time Pollutant Data: The Ontario Ministry of the Environment reports real-time O3, PM2.5, NO2, CO, and SO2 data in geographical, graphical and tabular formats every hour. See the newest results: Current Pollutant Concentrations.