About Air Quality in Ontario
Air quality in Ontario is monitored in real-time by sensors and measurement stations. On this page you'll find current data on major air pollutants including particulate matter PM2.5 and PM10, nitrogen dioxide (NO2), ozone (O3), and radiation levels.
Common Pollutants in Ontario
- PM2.5 - fine particulate matter up to 2.5 micrometers, particularly harmful to health
- PM10 - particulate matter up to 10 micrometers from traffic and industry
- NO2 - nitrogen dioxide mainly emitted by vehicles
- O3 - tropospheric ozone formed in photochemical reactions
When is Air Quality Best in Ontario?
Generally, the best air quality occurs:
- Early morning (5:00-7:00 AM) before rush hour traffic
- After rainfall which cleanses the atmosphere
- During strong winds that disperse pollutants
- In summer months when heating systems are less used
Tips for Runners in Ontario
If you're planning outdoor activities in Ontario, always check the current AQI value. When AQI exceeds 100, consider moving your workout indoors or shortening the distance. People with respiratory issues, children, and seniors should be especially cautious during elevated pollution levels. Choose routes away from busy streets and industrial areas.