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Air quality

  • Ground-level ozone, a key component of smog, has been linked to health issues ranging from minor respiratory problems to hospitalizations.
  • The national seasonal average concentration of ozone increased 16% from 1990 to 2003. Most monitoring stations are located in urban areas in southern Canada.
  • The highest seasonal average ozone concentrations in 2003 were all recorded at stations in Southern Ontario; concentrations in this region had also grown the fastest since 1990.


Ground-level ozone, a key component of smog, has significant negative effects on human health, on the natural environment and, consequently, on economic performance. Other important air pollutants include fine particles, sulphur oxides and carbon monoxide. More >>

Status and trends

National status and trends

In general, the health impacts of ozone worsen as concentrations increase. Seasonal ground-level ozone concentrations averaged approximately 40 parts per billion (ppb) in Canada in 2003 (Figure 1) and concentrations rose 16% from 1990 to 2003. More >>

What's next?

Future reports will address other air pollutants as well as ground-level ozone. Air contaminants that pose human health risks include, among others, fine particles, sulphur oxides, and carbon monoxide. More >>

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Date modified: 2005-12-14 Important Notices
Online catalogue Main page Executive summary Introduction Findings Conclusion Figures and maps Methods and data quality References More information PDF version Related products Online catalogue: Canadian Environmental Sustainability Indicators: Socio-economic Information