Canadian Smog Science Assessment Highlights and Key Messages

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Preamble

This “Highlights and Key Messages” document, a distillation of the material contained in the Canadian Smog Science Assessment, was co-authored by Environment Canada and Health Canada and presents a summary of the Assessment’s key findings¹. This initiative is the most recent effort² by the Government of Canada to assess the adverse effects of smog on Canadians and their environment, quantify emissions of smog-forming pollutants, describe their behaviour in the atmosphere at a regional scale, and report on recent and projected levels of smog in the air we breathe. It represents the first time all the scientific material related to smog in Canada has been addressed together, combining characterization of both particulate matter and ground-level ozone in a single document.

This summary document is intended to provide credible and relevant scientific information to guide current policy and regulatory decision-making in Canada. With this purpose in mind, the document has been arranged in a logical manner to inform risk management decision-making.

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Contents

• Introduction to Smog
• Effects on Human Health
  • Mortality
    • Chronic Exposure Mortality
    • Acute Exposure Mortality
    • Intervention Studies
    • Conclusions
  • Morbidity
    • Chronic Exposure Morbidity
    • Acute Exposure Morbidity--Hospital Admissions and Emergency Room Visits
    • Acute Exposure Morbidity--Panel Studies
    • Conclusions
    • Supporting Evidence from Other Types of Studies
• Effects on Ecosystem Health
• Effects on Social and Economic Wellbeing
• Levels of Smog in the Atmosphere
  • Recent Levels of Fine Particulate Matter (PM_2.5)
  • Composition of Secondary PM_2.5
  • Baseline Levels of PM_2.5
  • Trends in Ambient PM_2.5
  • Recent Levels of O₃
  • Temporal Variations in Ambient O₃ Levels
  • Baseline Levels of O₃
  • Trends in O₃ Levels
  • Projections of Future Levels of PM_2.5 and O₃
  • Relative Influence of Key Economic Sectors
• Factors Influencing Levels of Smog Across Canada
  • Meteorology
  • Coastal and Urban Effects
  • Local Chemical Mixture
  • Natural Emissions of Precursors
  • Transboundary Transport
• Sources of Smog Pollutants
  • Primary Particulate Matter (PM)
  • Nitrogen Oxides (NO_X)
  • Sulphur Dioxide (SO₂)
  • Volatile Organic Compounds (VOC)
  • Ammonia (NH₃)
  • Emissions Sources in the U.S.
• Emerging Issues
  • Climate Change
  • Intercontinental Transport
• Knowledge Gaps
• Recommendations for Future Research
  • Health Effects
  • Environmental Effects
  • Emissions
  • Monitoring and Trend Analysis
  • Understanding of Processes
  • Modelling
• Conclusions

¹. The Canadian Smog Science Assessment will be available in 2012.

². Previous assessments include:

Federal-Provincial Working Group on Air Quality Objectives and Guidelines, 1999. National ambient air quality objectives for ground-level ozone: Science assessment document. Health Canada and Environment Canada, Ottawa.

Federal-Provincial Working Group on Air Quality Objectives and Guidelines, 1999. National ambient air quality objectives for particulate matter, Part 1: Science assessment document. Health Canada and Environment Canada, Ottawa.

Joint Action Implementation Coordinating Committee, 2005. An Update in Support of the Canada-wide Standards for Particulate Matter and Ozone: Part A - 2003 science review. Report to the Canadian Council of Ministers of the Environment [Available at www.ccme.ca].