The state of air quality in Canada: National patterns

Abstract

This chapter provides a description of what air pollutants are routinely monitored in Canada and then focuses on ambient concentrations, geographic differences, temporal patterns and recent trends. In the context of the past 30-40 years, Canadian air quality has been an environmental management success story. Levels throughout the populated regions of the country are considerably lower than in the 1970's and 1980's. The 1990's also brought reductions and this chapter shows that even up through the 2000's improvements in air quality have been realized. However, these recent measurements indicate that there are areas where the current Canadian standards or provincial guidelines are still exceeded for ozone, PM2.5 and toxics. Ozone has been the most problematic although there has been improvement in recent years. Similarly, on a national scale PM2.5 has decreased. However, pollutants such as PM2.5 can have effects on the population at low levels. Thus, air quality remains an important public health issue to track in Canada through routine monitoring; nationally, regionally and at the local scale, where areas of concentrated emissions due to industrial activity or population behaviour (e.g., traffic, wood burning) can lead to higher population exposures. Monitoring is critical in regions of projected industrial or population growth in order to maintain current levels, to identify options for improvement and to inform adaptive management approaches.